Osteoporosis in Rheumatoid Arthritis: Dangerous Liaisons

Considerations for the use of biological therapies in elderly patients with rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease that primarily affects middle-aged individuals but is increasingly prevalent among the elderly due to longer life expectancies. Treating elderly onset RA (EORA) is challenging for clinicians because of unique disease characteristics, comorbidities, polypharmacy, age-related physiological changes, and limited studies on the safety and efficacy of biological therapies in this population. This review aims to evaluate the use of various biological therapies in elderly RA patients.

AREAS COVERED

This narrative review examines various aspects of RA in the elderly using published literature, randomized control trials, meta-analyses, and recommendations from the National Institute for Health and Care Excellence (NICE) and The European Alliance of Associations for Rheumatology (EULAR).

EXPERT OPINION

In EORA patients, the initiation of biological therapy is often delayed. Methotrexate remains the first-line treatment for both EORA and young onset RA (YORA). The combination of methotrexate and biological treatment shows comparable safety and efficacy in both EORA and YORA, except for rituximab, which is less effective in patients over 75. For elderly RA patients, biological (b-) disease-modifying antirheumatic drugs (DMARDs) are preferred as the first advanced therapy over targeted synthetic (ts-) DMARDs due to their superior safety profile.

Identification of critical genes and metabolic pathways in rheumatoid arthritis and osteoporosis toward drug repurposing

BACKGROUND

Rheumatoid arthritis (RA) and osteoporosis (OP) are considered to be complex diseases. In recent studies, a positive association between RA and OP has been reported triggering growing research interest. This study aims to investigate the drugs related to critical genes in RA and OP, using bioinformatics approaches, toward drug repurposing.

METHOD

RA and OP genes were identified. The RA-OP PPI network was constructed and analyzed using the STRING and Cytoscape, respectively. Hub genes and modules were extracted and enriched Gene Ontology, through the WebGestalt and g:Profiler. The identification of the drugs related to critical genes using the DGIDB, and extracted the miRNAs using miRWalk and miRNet.

RESULTS

By network clustering, five significant modules were obtained that have important roles in the immune system. IL6, TNF, IL1B, STAT3, TGFB1, TP53, HIF1A, CCL2, IL10, and MMP9 were found as the top 10 hub genes in the RA-OP network. Hub genes were shown to have implications in inflammatory response, significant functions in cytokine receptor binding, and localized mostly in extracellular space. By investigating the drugs related to hub genes, 16 drugs were identified as repurposing candidate drugs. The 10 drugs included Hydroxychloroquine, Infliximab, Adalimumab, Etanercept, Certolizumab, Cyclosporine, Diacerein, Gevokizumab, Canakinumab, and Olokizumab proposed for OP. Also, six drugs including Pirfenidone, Pentoxifylline, Vadimezan, Rilonacept, Metelimumab, and Siltuximab have important roles in inflammatory control and were proposed for both RA and OP.

CONCLUSIONS

The results of the present study can provide novel insights into the pathogenesis and treatment of RA and OP.

Hydroxychloroquine and risk of osteoporosis in patients with rheumatoid arthritis: A population-based retrospective study of 6408 patients

AIM

Patients with rheumatoid arthritis (RA) are at a higher risk of osteoporotic fractures. Studies have shown that patients with Sjogren's syndrome (SS) and systemic lupus erythematosus (SLE) experienced an increase in bone mineral density (BMD) after receiving hydroxychloroquine (HCQ) treatment, indicating a potential protective effect against osteoporosis. Therefore, this study is to examine the relationship between HCQ usage and the risk of osteoporosis in patients diagnosed with RA.

METHODS

The retrospective cohort study used data from Taiwan's National Health Insurance Research Database (NHIRD) covering the period from January 2010 to December 2018, which included 14 050 newly diagnosed RA patients, subsequently divided into two groups: HCQ users and non-users. Propensity score matching (PSM) based on sex, age, urbanization, insured unit type, insured area, and comorbidities was conducted to match the groups. The primary outcome assessed was the evaluation of the risk of osteoporosis by employing a multivariable Cox proportional hazard regression model to calculate the adjusted hazard ratio (aHR).

RESULTS

After PSM, a total of 6408 RA patients were included in the analysis (3204 HCQ users and 3204 non-users). There was no significantly higher risk of osteoporosis in HCQ users compared with non-users, aHR = 0.99 (95% CI: 0.82-1.196). Additionally, different durations of HCQ usage demonstrated a neutral effect on the risk of osteoporosis [HCQ <90 days, aHR = 0.88 (95% CI: 0.585-1.324); HCQ 90-180 days, aHR = 0.941 (95% CI: 0.625-1.418); HCQ >180 days, aHR = 1.019 (95% CI: 0.832-1.249)].

CONCLUSIONS

The study indicates that there is no significant association between the use of HCQ and the risk of osteoporosis in patients with RA.

Integration of bioinformatics and machine learning approaches for the validation of pyrimidine metabolism-related genes and their implications in immunotherapy for osteoporosis

BACKGROUND

Osteoporosis (OP), the "silent epidemic" of our century, poses a significant challenge to public health, predominantly affecting postmenopausal women and the elderly. It evolves from mild symptoms to pronounced severity, stabilizing eventually. Unique among OP's characteristics is the altered metabolic profile of affected cells, particularly in pyrimidine metabolism (PyM), a crucial pathway for nucleotide turnover and pyrimidine decomposition. While metabolic adaptation is acknowledged as a therapeutic target in various diseases, the specific role of PyM genes (PyMGs) in OP's molecular response remains to be clarified.

METHODS

In pursuit of elucidating and authenticating PyMGs relevant to OP, we embarked on a comprehensive bioinformatics exploration. This entailed the integration of Weighted Gene Co-expression Network Analysis (WGCNA) with a curated list of 37 candidate PyMGs, followed by the examination of their biological functions and pathways via Gene Set Variation Analysis (GSVA). The Least Absolute Shrinkage and Selection Operator (LASSO) technique was harnessed to identify crucial hub genes. We evaluated the diagnostic prowess of five PyMGs in OP detection and explored their correlation with OP's clinical traits, further validating their expression profiles through independent datasets (GSE2208, GSE7158, GSE56815, and GSE35956).

RESULTS

Our analytical rigor unveiled five PyMGs-IGKC, TMEM187, RPS11, IGLL3P, and GOLGA8N-with significant ties to OP. A deeper dive into their biological functions highlighted their roles in estrogen response modulation, cytosolic calcium ion concentration regulation, and GABAergic synaptic transmission. Remarkably, these PyMGs emerged as potent diagnostic biomarkers for OP, distinguishing affected individuals with substantial accuracy.

CONCLUSIONS

This investigation brings to light five PyMGs intricately associated with OP, heralding new avenues for biomarker discovery and providing insights into its pathophysiological underpinnings. These findings not only deepen our comprehension of OP's complexity but also herald the advent of more refined diagnostic and therapeutic modalities.

The interplay of rheumatoid arthritis and osteoporosis: exploring the pathogenesis and pharmacological approaches

Rheumatoid arthritis (RA) and osteoporosis are two chronic disorders that are often seen together. RA is an autoimmune disorder that causes pain and inflammation in the joints, while osteoporosis is a disorder in which the bones become weak and fragile. Risk factors for bone loss in RA include disease activity, longer disease duration, erosive disease, autoantibody positivity, and joint damage leading to impaired physical activity. Recent research has shown that there is a complex interplay between immune cells, cytokines, and bone remodeling processes in both RA and osteoporosis. The bone remodeling process is regulated by cytokines and immune system signaling pathways, with osteoclasts activated through the RANK/RANKL/OPG pathway and the Wnt/DKK1/sclerostin pathway. Understanding these mechanisms can aid in developing targeted therapies for treatment of osteoporosis in RA patients. Current pharmacological approaches include anti-osteoporotic drugs such as bisphosphonates, denosumab, teriparatide, abaloparatide, raloxifene, and romosozumab. Conventional disease-modifying antirheumatic drugs such as methotrexate and biologicals including TNF inhibitors, IL-6 inhibitors, rituximab, and abatacept lower disease activity in RA and can improve bone metabolism by reducing inflammation but have limited impact on bone mineral density. This review will shed light on the relationship between osteoporosis and rheumatoid arthritis as well as the various factors that influence the onset of osteoporosis in RA patients. We also explore several treatment approaches to effectively managing osteoporosis in RA patients.

Correlation of serum matrix metalloproteinase 3 with osteoporosis in patients of postmenopausal rheumatoid arthritis

Osteoporosis (OP) is a common complication of postmenopausal women with rheumatoid arthritis (RA). Herein, the objective of our study was to explore the correlation between serum matrix metalloproteinase 3 (MMP3) and OP among postmenopausal women with RA to foster better diagnosis and treatment. A total of 208 elderly postmenopausal women with RA were included in this study, with 83 patients diagnosed with OP after RA diagnosis and 125 patients without OP. Serum MMP3 levels and bone mineral density (BMD) were measured and compared. The predictive value of serum MMP3 for OP in this population was also analyzed using receiver operating curve (ROC) analysis. Postmenopausal women with RA and OP diagnosis had markedly higher serum MMP3 levels, compared to those without OP. ROC analysis showed that serum MMP3 had predictive value for OP. Additionally, a negative correlation was observed between serum MMP3 levels and BMD. High serum MMP3 levels were also found to be associated with high abnormal bone metabolism. We found that serum MMP3 levels are strongly correlated with OP in postmenopausal women with RA and that elevated levels of serum MMP3 are linked to low BMD and high abnormal bone metabolism. Serum MMP3 may be a useful biomarker for predicting OP in this population, and could potentially aid in the development of targeted prevention and treatment strategies.

Real-time analysis of osteoclast resorption and fusion dynamics in response to bone resorption inhibitors

Cathepsin K (CatK), an essential collagenase in osteoclasts (OCs), is a potential therapeutic target for the treatment of osteoporosis. Using live-cell imaging, we monitored the bone resorptive behaviour of OCs during dose-dependent inhibition of CatK by an ectosteric (Tanshinone IIA sulfonate) and an active site inhibitor (odanacatib). CatK inhibition caused drastic reductions in the overall resorption speed of OCs. At IC50 CatK-inhibitor concentration, OCs reduced about 40% of their trench-forming capacity and at fourfold IC50 concentrations, a > 95% reduction was observed. The majority of CatK-inhibited OCs (~ 75%) were involved in resorption-migration-resorption episodes forming adjacent pits, while ~ 25% were stagnating OCs which remained associated with the same excavation. We also observed fusions of OCs during the resorption process both in control and inhibitor-treated conditions, which increased their resorption speeds by 30-50%. Inhibitor IC50-concentrations increased OC-fusion by twofold. Nevertheless, more fusion could not counterweigh the overall loss of resorption activity by inhibitors. Using an activity-based probe, we demonstrated the presence of active CatK at the resorbing front in pits and trenches. In conclusion, our data document how OCs respond to CatK-inhibition with respect to movement, bone resorption activity, and their attempt to compensate for inhibition by activating fusion.

Recent advances in senescence-associated secretory phenotype and osteoporosis

The worldwide elderly population is on the rise, and aging is a major osteoporosis risk factor. Senescent cells accumulation can have a detrimental effect the body as we age. The senescence-associated secretory phenotype (SASP), an essential cellular senescence hallmark, is an important mechanism connecting cellular senescence to osteoporosis. This review describes in detail the characteristics of SASPs and their regulatory agencies, and shed fresh light on how SASPs from different senescent cells contribute to osteoporosis development. Furthermore, we summarized various innovative therapy techniques that target SASPs to lower the burden of osteoporosis in the elderly and discussed the potential challenges of SASPs-based therapy for osteoporosis as a new clinical trial.

Prediction of osteoporosis in patients with rheumatoid arthritis using machine learning

Osteoporosis is a serious health concern in patients with rheumatoid arthritis (RA). Machine learning (ML) models have been increasingly incorporated into various clinical practices, including disease classification, risk prediction, and treatment response. However, only a few studies have focused on predicting osteoporosis using ML in patients with RA. We aimed to develop an ML model to predict osteoporosis using a representative Korean RA cohort database. The KORean Observational study Network for Arthritis (KORONA) database, established by the Clinical Research Center for RA in Korea, was used in this study. Among the 5077 patients registered in KORONA, 2374 patients were included in this study. Four representative ML algorithms were used for the prediction: logistic regression (LR), random forest, XGBoost (XGB), and LightGBM. The accuracy, F1 score, and area under the curve (AUC) of each model were measured. The LR model achieved the highest AUC value at 0.750, while the XGB model achieved the highest accuracy at 0.682. Body mass index, age, menopause, waist and hip circumferences, RA surgery, and monthly income were risk factors of osteoporosis. In conclusion, ML algorithms are a useful option for screening for osteoporosis in patients with RA.

Whole-hand and regional bone mineral density involvement in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by symmetric polyarthritis that can lead to joint deformity, disability, and osteoporosis. We aimed to evaluate whole hand and regional BMD in RA patients compared to controls. In addition, we evaluated the BMD of dominant versus non-dominant hands in healthy subjects. We included adult female and male RA patients and control subjects matched by age, sex, and BMI. BMD (g/cm2) was measured by DXA in lumbar spine (LS), whole hand, and three regions of interest: carpus, metacarpal bones, and phalanges. Results: 44 control subjects (49.5±11.8 y) and 60 with RA (52.7±12.7 y) were included. Significant lower BMD in RA patients was found in LS (-8.7%), dominant whole hand (-9.5%), carpus, metacarpal bones, and phalanges, and non-dominant whole hand (-8.7%), metacarpal bones, and phalanges compared to controls. A significant positive correlation was found between LS and whole-hand BMD (dominant r=.63, non-dominant r=.67). Finally, the whole hand, metacarpal bones, and carpus BMD measurements were significantly higher in the dominant hand compared to the non-dominant hand without differences in the phalangeal ROI. In conclusion, hand BMD was significantly lower in RA patients compared to control subjects and there was a significant correlation with LS BMD. We demonstrated that BMD measurements of the whole-hand, and different ROI (carpus, metacarpal bones, and phalanges) by DXA would be an easily reproducible technique to evaluate bone loss. In addition, the whole hand, metacarpal bones and carpus BMD measurements were significantly higher in the dominant hand compared to the non-dominant hand without differences in the phalanges.

Effect of Hypertension on Bone Mineral Density of Patients with Rheumatoid Arthritis

Objective

Patients with rheumatoid arthritis (RA) are associated with low bone mineral density (BMD). Chronic comorbidities such as type II diabetes mellitus have shown to affect BMD parameters in patients with RA. Hypertension (HT) is a chronic disease and its coexistence with RA can alter bone health. The aim of this study was to investigate if HT affected BMD parameters in RA patients diagnosed for the first time.

Methods

Patients with the diagnosis of RA who underwent BMD studies formed the study population. Patients with HT were sorted from this population and formed a separate group. Healthy controls were drawn from subjects who came for a check-up. BMD was done with the GE Lunar DPX machine. Mean T Scores at spine, femur neck and total femur were recorded. Data from the three groups were analysed and compared. Linear regression analyses were performed.

Results

Analysis suggested that the age had inverse and BMI had direct correlation with BMD T scores in all groups. The additional diagnosis of HT in RA patients was associated with higher BMD as compared to patients with RA, but lower than controls. R2 values were 0.341, 0.402 and 0.436 for mean T scores at spine, femur neck and femur total respectively. Figures from multiple regression analysis suggest that BMI alone did not explain the higher T score values in HT patients.

Conclusion

Additional morbidity of HT in RA patients negates the porotic effect of RA as judged by bone densitometry. Hence, BMD reports should be read with caution in these patients.

Osteoporosis in Black South Africans With Rheumatoid Arthritis

Background Osteoporosis is a common comorbidity associated with rheumatoid arthritis (RA). The aim of this study was to determine the risk factors and possible predictors of osteoporosis in black patients with RA. Methods A retrospective study of 120 randomly selected RA patients attending an arthritis clinic in Johannesburg, South Africa, was carried out, in which 60 patients were with and 60 without osteoporosis. The demographics, disease activity, American College of Rheumatology (ACR) functional status, treatment, and dual-energy X-ray absorptiometry (DEXA) characteristics were compared. Statistical analysis was performed using SPSS version 25.0 (IBM Corp, Armonk, NY). Bivariate comparisons of demographic factors, disease factors, and T-scores between patients with and without osteoporosis were performed, using two-sided t-tests for continuous variables and chi-squared tests for categorical variables. Possible predictors of osteoporosis were subsequently entered into a multivariate logistic regression model with osteoporosis being the dependent variable. The level of significance for all analyses was set at p < 0.05. Results The median (IQR) age of the overall cohort was 67 (61.0, 72.8) years, the majority (95.5%) were female, of which 97.4% were postmenopausal. The mean disease duration from diagnosis to the DEXA was 8.6 ± 6.2 years. Rheumatoid factor (RF) positivity was 89.2% and anti-cyclic citrullinated peptide (ACCP) positivity was 82.7%. The median (IQR) for disease activity score 28 swollen and tender joint count using the erythrocyte sedimentation rate (DAS-28 ESR) was 3.4 (2.8-4.7) and the median (IQR) for ESR was 41 (22, 64.3) mm/h. There were significantly more patients treated with triple therapy in the no osteoporosis group, 38 (63.3%), than in the osteoporosis group, 21 (35%) (p = 0.00). The ACR functional class was significantly worse in the RA patients with osteoporosis than in the RA patients without osteoporosis [median (IQR), 2 (2, 3) vs 2 (1, 2), (p = 0.03)], respectively. Conclusion This study found that a worse ACR functional class was significantly associated with osteoporosis. In addition, the use of triple therapy had a protective effect. Early recognition of the risk factors for osteoporosis should be sought, with prompt preventative measures, screening, and treatment.

Validating the Fracture Risk Assessment Tool Score in a US Population-Based Study of Patients With Rheumatoid Arthritis

OBJECTIVE

The World Health Organization fracture risk assessment tool (FRAX) algorithm for risk prediction of major osteoporotic and hip fractures accounts for several risk factors, including rheumatoid arthritis (RA), since individuals with RA have an excess burden of fractures. FRAX has not been validated in population-based RA cohorts in the US. We aimed to determine the accuracy of FRAX predictions for individuals with RA in the US.

METHODS

This retrospective population-based cohort study included residents of Olmsted County, Minnesota, who were followed until death, migration, or last medical record review. Each patient with RA (1987 American College of Rheumatology criteria met in 1980-2007, age 40-89 years) was matched 1:1 on age and sex to an individual without RA from the same underlying population. Ten-year predictions for major osteoporotic and hip fractures were estimated using the FRAX tool. Fractures were ascertained through follow-up, truncated at 10 years. Standardized incidence ratios (SIRs) and 95% CI were calculated to compare observed and predicted fractures.

RESULTS

The study included 662 patients with RA and 658 non-RA comparators (66.8% vs 66.9% female and a mean age of 60.6 vs 60.5 years, respectively). Among patients with RA, 76 major osteoporotic fractures and 21 hip fractures were observed during follow-up (median follow-up: 9.0 years) compared to 67.0 predicted major osteoporotic fractures (SIR 1.13, 95% CI 0.91-1.42) and 23.3 predicted hip fractures (SIR 0.90, 95% CI 0.59-1.38). The observed and predicted major osteoporotic and hip fracture risks were similar for patients with RA and non-RA comparators.

CONCLUSION

The FRAX tool is an accurate method for estimating major osteoporotic and hip fracture risk in patients with RA.

Factors associated with radiographic progression in rheumatoid arthritis starting biological diseases modifying anti-rheumatic drugs (bDMARDs)

Background

Biological DMARDs (bDMARDs) have been proven to prevent joint damage and bone erosions. Nevertheless, approximately 15% of rheumatoid arthritis (RA) patients on bDMARDs will progress despite good control of joint inflammation.

Objectives

The objective of our study is to investigate the factors associated with radiological progression of patients treated with bDMARDs.

Design

We conducted a retrospective analysis of longitudinally collected data on RA patients starting bDMARDs.

Methods

Presence or development of new erosions was assessed by a skilled rheumatologist at the time of the visit (baseline and 12 months thereafter). To determine the predictors of erosions, we employed multivariable logistic regression models. Discriminatory capacity for the prediction of new erosion development was assessed with receiver operating characteristic (ROC) curve, which was based on the logistic regression model.

Results

A total of 578 RA patients starting bDMARDs were included in the study. Overall, 46 patients (approximately 10%) had radiographic progression (at least one new erosion) at 12 months of follow-up. The factors independently associated with higher risk of developing new erosions while on bDMARD were younger age, high disease activity at baseline, not being treated with cDMARDs, and presenting with erosions at baseline. In addition, we built a predictive model that can accurately foresee new erosions (AUC 0.846) in patients receiving bDMARDs.

Conclusion

We found that baseline erosive disease, higher disease activity during treatment, younger age, and monotherapy were the factors independently associated with the development of bone erosions. Our study may inform future targeted intervention in RA patients at risk of radiographic progression.

Sex differences in long-term effects of collagen-induced arthritis in middle-aged mice

Introduction: Rheumatoid arthritis (RA) is a chronic inflammatory disorder with high prevalence among middle-aged women. Collagen-induced arthritis (CIA) is the most widely used animal model of RA, however, sex differences and long-term effects of CIA in mice are poorly described in the literature. Aim: Therefore, the present study aimed to analyze the long-term effects of CIA on the joints of middle-aged mice of both sexes and to describe potential sex differences. Materials and methods: CIA was induced in middle-aged DBA/1J mice by immunization with bovine type II collagen and complete Freund's adjuvant. Saline was administered to control mice. Arthritis score assessment, plethysmometry, and thermal imaging of the joints were performed weekly for 15 weeks. Locomotor activity, micro-computed tomography, joint histology and biochemical analyses were performed at the end of the experiment. Results: Our results indicate a similar prevalence of arthritis in both sexes of mice-67% (8/12) of females and 89% (8/9) males with an earlier onset in males (day 14 vs. day 35). After the arthritis scores peaked on day 56 for males and day 63 for females, they steadily declined until the end of the experiment on day 105. A similar dynamics was observed in paw volume and temperature analyzing different aspects of joint inflammation. Long-term consequences including higher proteinuria (by 116%), loss of bone density (by 33.5%) and joint damage in terms of synovial hyperplasia as well as bone and cartilage erosions were more severe in CIA males compared to CIA females. There were no significant differences in locomotor activity between CIA mice and CTRL mice of any sex. Conclusion: This is the first study to describe the long-term effects of the CIA model in terms of sex differences in DBA/1J mice. Our results indicate sex differences in the dynamics, but not in the extent of arthritis. An earlier onset of arthritis and more severe consequences on joints, bones and kidneys were found in males. The underlying immune pathomechanisms responsible for the limited duration of the arthritis symptoms and the opposite sex difference in comparison to RA patients require further investigation.

Does Dietary Polyunsaturated Fatty Acid Intake Associate With Bone Mineral Density and Limb Structural Changes in Early Rheumatoid Arthritis?

Background

Rheumatoid arthritis (RA) is an inflammatory disease that can result in bone erosion, lean mass lowering, and increase of fat mass without changes in body weight. The dietary consumption of polyunsaturated fatty acids (PUFAs) has been assessed in many studies due to their potential anti-inflammatory effect.

Aim

The aim of this research was to identify if dietary intake of PUFAs associates with bone mineral density (BMD) and limb structural changes in early rheumatoid arthritis (ERA) compared to a population-based control group. The study was conducted because previous results have been insufficient.

Methods

The study group consisted of 83 ERA patients and 321 control subjects. A dual-energy X-Ray absorptiometry (DXA) machine was used to measure hip, lumbar spine, and radius BMD, as well as arm and leg fat, lean, and bone mass. Dietary habits and inflammatory markers were assessed to evaluate the effects to BMD and limb structural changes.

Results

In ERA subjects, higher dietary consumption of PUFAs was associated with a decrease in arm fat mass (b -28.17, P = .02) and possibly with higher lumbar BMD (b 0.008, P = .058). Limb bone and lean mass changes were not associated with dietary intake of PUFAs.

Conclusion

Balanced nutrition is essential. Consuming PUFAs could be beneficial in ERA preventing structural changes to hands, but additional research is needed.

Computational Drug Discovery in Ankylosing Spondylitis-Induced Osteoporosis Based on Data Mining and Bioinformatics Analysis

BACKGROUND

Ankylosing spondylitis (AS) and osteoporosis (OP) are both prevalent illnesses in spine surgery, with OP being a possible consequence of AS. However, the mechanism of AS-induced OP (AS-OP) remains unknown, limiting etiologic research and therapy of the illness. To mine targetable medicine for the prevention and treatment of AS-OP, this study analyzes public data sets using bioinformatics to identify genes and biological pathways relevant to AS-OP.

METHODS

First, text mining was used to identify common genes associated with AS and OP, after which functional analysis was carried out. The STRING database and Cytoscape software were used to create protein-protein interaction networks. Hub genes and potential drugs were discovered using drug-gene interaction analysis and transcription factors-gene interaction analysis.

RESULTS

The results of text mining showed 241 genes common to AS and OP, from which 115 key symbols were sorted out by functional analysis. As options for treating AS-OP, protein-protein interaction analysis yielded 20 genes, which may be targeted by 13 medications.

CONCLUSIONS

Carlumab, bermekimab, rilonacept, rilotumumab, and ficlatuzumab were first identified as the potential drugs for the treatment of AS-OP, proving the value of text mining and pathway analysis in drug discovery.

Chronic arthritides and bone structure: focus on rheumatoid arthritis-an update

Normal bone remodeling depends of a balance between bone forming cells, osteoblasts and bone resorbing cells, the osteoclasts. In chronic arthritides and some inflammatory and autoimmune diseases such as rheumatoid arthritis, there is a great constellation of cytokines produced by pannus that impair bone formation and stimulate bone resorption by inducing osteoclast differentiation and inhibiting osteoblast maturation. Patients with chronic inflammation have multiple causes that lead to low bone mineral density, osteoporosis and a high risk of fracture including circulating cytokines, impaired mobility, chronic administration of glucocorticoids, low vitamin D levels and post-menopausal status in women, among others. Biologic agents and other therapeutic measures to reach prompt remission might ameliorate these deleterious effects. In many cases, bone acting agents need to be added to conventional treatment to reduce the risk of fractures and to preserve articular integrity and independency for daily living activities. A limited number of studies related to fractures in chronic arthritides were published, and future investigation is needed to determine the risk of fractures and the protective effects of different treatments to reduce this risk.

Tubson-2 decoction ameliorates rheumatoid arthritis complicated with osteoporosis in CIA rats involving isochlorogenic acid A regulating IL-17/MAPK pathway

BACKGROUND

Osteoporosis (OP) is considered as one of the major comorbidities of rheumatoid arthritis (RA), and is responsible for fragility fracture. However, there is currently no effective treatment for RA complicated with OP. Tubson-2 decoction (TBD), a Mongolian medicine also known as Erwei Duzhong Decoction, has been shown to exert a preventive effect on post-menopausal osteoporosis (PMOP). The preventive effects of TBD on RA-induced OP, as well as the bioactive compound responsible and the underlying mechanisms, remain to be elucidated.

OBJECTIVE

To explore the effects of TBD on RA-induced OP in vivo, and to elucidate the mechanism of isochlorogenic acid A (ICA), the effective component of TBD, in vitro.

METHODS

To evaluate the anti-arthritic and anti-osteoporotic effects of TBD, we conducted H&E straining and safranine O/fast green, TEM, immunohistochemistry (IHC), bone histomorphometry, micro-CT imaging, and biomechanical testing in collagen induced arthritis (CIA) rats. The active ingredient in TBD was identified using network pharmacology and molecular docking. The identification was supported by in vivo IHC assay, and further confirmed using qRT-PCR, Western blot, and SEM analysis in TNF-α-treated MH7A cells and/or in LPS-exposed RAW264.7 cells.

RESULTS

Oral administration of TBD attenuated the severity of arthritis and osteopenia as well as poor bone quality, in CIA rats. Additionally, TBD and the positive control, tripterygium glycosides (TG), exhibited similar effects in reducing inflammation in both the synovium and ankle joint. They also were both effective in improving bone loss, microarchitecture, and overall bone quality. TBD reduced the expression of MMP13, IL-17, and p-JNK protein in the synovium of CIA rats. ICA, which was screened, suppressed TNF-α or LPS-triggered inflammatory responses via down-regulating IL-17 signaling, involving in MMP13, IL-1β, IL-23, and IL-17, and the MAPK pathway including p-ERK, p-JNK, and p-P38, both in MH7A cells and in RAW264.7 cells. Furthermore, ICA prevented osteoclasts from differentiating and bone resoprtion in a dose-dependent manner in vitro.

CONCLUSION

This study provides the first evidence that TBD exerts intervening effects on RA-induced OP, possibly through the downregulation of the IL-17/MAPK signaling pathway by ICA. The findings of our study provides valuable insights for further research in this area.

Revisiting Resveratrol as an Osteoprotective Agent: Molecular Evidence from In Vivo and In Vitro Studies

Resveratrol (RSV) (3,5,4'-trihydroxystilbene) is a stilbene found in abundance in berry fruits, peanuts, and some medicinal plants. It has a diverse range of pharmacological activities, underlining the significance of illness prevention and health promotion. The purpose of this review was to delve deeper into RSV's bone-protective properties as well as its molecular mechanisms. Several in vivo studies have found the bone-protective effects of RSV in postmenopausal, senile, and disuse osteoporosis rat models. RSV has been shown to inhibit NF-κB and RANKL-mediated osteoclastogenesis, oxidative stress, and inflammation while increasing osteogenesis and boosting differentiation of mesenchymal stem cells to osteoblasts. Wnt/β-catenin, MAPKs/JNK/ERK, PI3K/AKT, FoxOs, microRNAs, and BMP2 are among the possible kinases and proteins involved in the underlying mechanisms. RSV has also been shown to be the most potent SIRT1 activator to cause stimulatory effects on osteoblasts and inhibitory effects on osteoclasts. RSV may, thus, represent a novel therapeutic strategy for increasing bone growth and reducing bone loss in the elderly and postmenopausal population.

Pathogenesis of Extraarticular Manifestations in Rheumatoid Arthritis-A Comprehensive Review

Rheumatoid arthritis (RA) is among the most prevalent and debilitating autoimmune inflammatory chronic diseases. Although it is primarily characterized by destructive peripheral arthritis, it is a systemic disease, and RA-related extraarticular manifestations (EAMs) can affect almost every organ, exhibit a multitude of clinical presentations, and can even be asymptomatic. Importantly, EAMs largely contribute to the quality of life and mortality of RA patients, particularly substantially increased risk of cardiovascular disease (CVD) which is the leading cause of death in RA patients. In spite of known risk factors related to EAM development, a more in-depth understanding of its pathophysiology is lacking. Improved knowledge of EAMs and their comparison to the pathogenesis of arthritis in RA could lead to a better understanding of RA inflammation overall and its initial phases. Taking into account that RA is a disorder that has many faces and that each person experiences it and responds to treatments differently, gaining a better understanding of the connections between the joint and extra-joint manifestations could help to create new treatments and improve the overall approach to the patient.

Engineering approaches to investigate the roles of lymphatics vessels in rheumatoid arthritis

Rheumatoid arthritis (RA) is one of the most common chronic inflammatory joint disorders. While our understanding of the autoimmune processes that lead to synovial degradation has improved, a majority of patients are still resistant to current treatments and require new therapeutics. An understudied and promising area for therapy involves the roles of lymphatic vessels (LVs) in RA progression, which has been observed to have a significant effect on mediating chronic inflammation. RA disease progression has been shown to correlate with dramatic changes in LV structure and interstitial fluid drainage, manifesting in the retention of distinct immune cell phenotypes within the synovium. Advances in dynamic imaging technologies have demonstrated that LVs in RA undergo an initial expansion phase of increased LVs and abnormal contractions followed by a collapsed phase of reduced lymphatic function and immune cell clearance in vivo. However, current animal models of RA fail to decouple biological and biophysical factors that might be responsible for this lymphatic dysfunction in RA, and a few attempted in vitro models of the synovium in RA have not yet included the contributions from the LVs. Various methods of replicating LVs in vitro have been developed to study lymphatic biology, but these have yet not been integrated into the RA context. This review discusses the roles of LVs in RA and the current engineering approaches to improve our understanding of lymphatic pathophysiology in RA.

Therapeutic effects of kefir peptides on adjuvant-induced arthritis in rats through anti-inflammation and downregulation of matrix metalloproteinases

AIMS

Rheumatoid arthritis (RA) is a chronic autoimmune disease. Its pathological features are synovial inflammation, bone erosion, and joint structural damages. Our previous studies have shown that kefir peptides (KPs) can reduce cardiovascular disease, osteoporosis and renal inflammation. In this study, we further evaluate the efficacy of KPs on adjuvant-induced arthritis (AIA) in a rat model.

MAIN METHODS

After the 14th day of adjuvant induction, rats were subsequently orally administered KPs (83 or 166 mg/day/kg) or tofacitinib (6.2 mg/day/kg) for 14 days. On the 28th day, the rats were anesthetized with isoflurane for ultrasonic, in vivo imaging system (IVIS), and radiographic imaging and then sacrificed for ankle tissues collection and analysis. In vitro, IL-1β-treated human synovial cells (SW982) were subjected to anti-arthritis mechanism study in the presence of KPs.

KEY FINDINGS

The results of ultrasonography, radiograph, histology, the expression of matrix metalloproteinases (MMPs), inflammatory cytokines and RANKL/OPG ratio demonstrated decreasing severity of synovitis and bone erosion in the ankle joints after KPs treatment. Activation of the NF-κB and MAPK pathways was significantly reduced in KPs treated AIA group. Furthermore, KPs attenuated IL-1β-induced inflammatory cytokine production and the expression of MMPs in a human synovial cell line SW982. These results demonstrated that KPs alleviated adjuvant-induced arthritis in rats by inhibiting IL-1β-related inflammation and MMPs production.

SIGNIFICANCE

We concluded that KPs can exhibit anti-inflammatory effects by reducing the levels of macrophage-related inflammatory cytokines and MMPs, thus alleviating bone erosion in the ankle joint and constituting a potential therapeutic strategy for rheumatoid arthritis.

Factors associated with hand bone changes in early rheumatoid arthritis

BACKGROUND

The aim of this research was to assess if hand bone mineral density (HBMD) changes associated with the appearance of erosions in early rheumatoid arthritis (ERA), compared with the population-based control group. Additionally, we tried to identify if there are novel factors that associate with HBMD and erosive changes (EC), and if they are dissimilar. The study was conducted as the data are limited.

METHODS

The study group consisted of 83 ERA patients and 321 controls. Dual-Energy X-Ray Absorptiometry (DXA) machine was used to measure HBMD. EC of RA (rheumatoid arthritis) were assessed in X-rays of hands using Sharp scores. Life-style habits, inflammation markers were assessed to evaluate the effects of different factors.

RESULTS

The presence of ERA was associated with lower HBMD compared with controls (adjusted for age, gender, height and weight; b -0.01, p = 0.045). 76% (95% CI 65.3-84.6) of ERA patients had EC in hand X-ray. Smoking habits and higher BMI (body mass index) were associated with an increased likelihood of having RA specific EC. In ERA, decreasing of HBMD was associated with the elevation of interleukin-6 (IL-6) and rheumatoid factor (RF) positivity.

CONCLUSIONS

In ERA, HBMD changes were not associated with the appearance of erosions. Factors that associate in ERA with HBMD changes and appearance of erosions differ. HBMD assessment together with serum IL-6 level could be useful in everyday clinical practice for better surveillance of ERA patients who do not have EC in hand X-rays.

Changes in Bone Metabolism in Patients with Rheumatoid Arthritis during Tumor Necrosis Factor Inhibitor Therapy

Tumor necrosis factor alpha (TNF-α), which enhances osteoclast activity and bone resorption, is one of the key inflammation mediators in rheumatoid arthritis (RA). The aim of this study was to assess the influence of yearlong TNF-α inhibitor application on bone metabolism. The study sample comprised 50 female patients with RA. Analyses involved the osteodensitometry measurements obtained using a "Lunar" type apparatus and the following biochemical markers from serum: procollagen type 1 N-terminal propeptide (P1NP), beta crosslaps C-terminal telopeptide of collagen type I (b-CTX) by ECLIA method, total and ionized calcium, phosphorus, alkaline phosphatase, parathyroid hormone and vitamin D. Analyses revealed changes in bone mineral density (BMD) at L1-L4 and the femoral neck, with the difference in mean BMD (g/cm²) not exceeding the threshold of statistical significance (p = 0.180; p = 0.502). Upon completion of 12-month therapy, a significant increase (p < 0.001) in P1NP was observed relative to b-CTX, with mean total calcium and phosphorus values following a decreasing trend, while vitamin D levels increased. These results suggest that yearlong application of TNF inhibitors has the capacity to positively impact bone metabolism, as indicated by an increase in bone-forming markers and relatively stable BMD (g/cm²).

A green-lipped mussel prevents rheumatoid arthritis via regulation of inflammatory response and osteoclastogenesis

Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by progressive joint destruction. Green-lipped mussel (GLM) has chondro-modulatory and anti-inflammatory properties, but the mechanism underlying the effect of GLM on RA is unclear. To investigate the roles of GLM on the pathogenesis of RA, we examined the effects of GLM in collagen-induced arthritis (CIA) mice and osteoclast differentiation. GLM was orally administrated CIA mice at 3 weeks after chicken type II collagen (CII) immunizations. GLM reduced arthritis severity and the histologic score of CIA mice compared to vehicle. The expression of proinflammatory cytokines (TNF-α, IL-1β, and IL-17) was decreased in the ankle joints of GLM-treated CIA mice. The expression of CD4+ IL-17+ cells decreased in ex vivo splenocytes and the spleens of GLM-treated CIA mice. Moreover, GLM inhibited TRAP+ multinucleated cells among mouse bone marrow-derived monocytes/macrophages (BMM), and the expression of osteoclast-related genes in mouse BMMs and human monocytes in vitro. These results suggest that GLM has potential as a therapeutic agent that can improve disease by controlling pathologic immune cells and osteoclastogenesis.

Positive Effects of Biologics on Osteoporosis in Rheumatoid Arthritis

Osteoporosis is a systemic skeletal disorder that causes vulnerability of bones to fracture owing to reduction in bone density and deterioration of the bone tissue microstructure. The prevalence of osteoporosis is higher in patients with autoimmune inflammatory rheumatic diseases, including rheumatoid arthritis (RA), than in those of the general population. In this autoimmune inflammatory rheumatic disease, in addition to known risk factors for osteoporosis, various factors such as chronic inflammation, autoantibodies, metabolic disorders, drugs, and decreased physical activity contribute to additional risk. In RA, disease-related inflammation plays an important role in local or systemic bone loss, and active treatment for inflammation can help prevent osteoporosis. In addition to conventional synthetic disease-modifying anti-rheumatic drugs that have been traditionally used for treatment of RA, biologic DMARDs and targeted synthetic DMARDs have been widely used. These agents can be employed more selectively and precisely based on disease pathogenesis. It has been reported that these drugs can inhibit bone loss by not only reducing inflammation in RA, but also by inhibiting bone resorption and promoting bone formation. In this review, the pathogenesis and research results of the increase in osteoporosis in RA are reviewed, and the effects of biological agents on osteoporosis are discussed.

Fracture in clinical studies of tofacitinib in rheumatoid arthritis

Background

Preclinical data suggest that tofacitinib would protect bone health in patients with rheumatoid arthritis (RA).

Objective

To assess fracture risk in tofacitinib RA clinical trials.

Design

Post hoc analysis.

Methods

We analyzed pooled data of phase I/II/III and long-term extension studies ('P123LTE cohort'), pooled data of placebo-controlled portions of phase III studies (phase III placebo-controlled cohort), and data from ORAL Surveillance [phase IIIb/IV randomized, open-label trial evaluating tofacitinib 5/10 mg twice daily (BID) vs tumor necrosis factor inhibitor (TNFi) in patients ⩾ 50 years with ⩾ 1 additional cardiovascular risk factor].

Results

In the phase III placebo-controlled cohort, incidence rates (IRs) [95% confidence interval (CI)] of fracture were 2.11 (1.09-3.68), 2.56 (1.23-4.71), and 4.43 (1.78-9.12) per 100 patient-years (PYs) for tofacitinib 5 mg BID, tofacitinib 10 mg BID, and placebo, respectively [tofacitinib 5 mg BID vs placebo: hazard ratio (HR) (95% CI) = 0.55(0.18-1.65); tofacitinib 10 mg BID vs placebo: HR (95% CI) = 0.72 (0.26-2.01)]. In P123LTE, IRs (95% CI) were 2.62 (2.29-2.99) and 2.26 (2.02-2.52) per 100 PY for average tofacitinib 5 and 10 mg BID, respectively. In ORAL Surveillance, IRs (95% CI) were 2.79 (2.34-3.30), 2.87 (2.40-3.40), and 2.27 (1.87-2.74) per 100 PY for tofacitinib 5 mg BID, tofacitinib 10 mg BID, and TNFi, respectively. In ORAL Surveillance, the risk of fracture was numerically higher than TNFi for tofacitinib 5 mg BID [HR (95% CI) = 1.23 (0.96-1.58)] and tofacitinib 10 mg BID [HR (95% CI) = 1.26 (0.97-1.62)]. In ORAL Surveillance, independent predictors of all and osteoporotic fractures with tofacitinib or TNFi included age ⩾ 65, female sex, history of fracture/osteoporosis, and baseline oral corticosteroid use.

Conclusion

This post hoc analysis showed numerically lower fracture risk with tofacitinib versus placebo and numerically greater risk versus TNFi. We did not identify any tofacitinib-specific predictors of fractures, and predictors of fracture were generally aligned with prior literature in the general population and patients with RA. Patients with fracture risk factors should be adequately monitored and treated.

Clinical trial registration

NCT00960440, NCT00847613, NCT00814307, NCT00856544, NCT00853385, NCT01039688, NCT02187055, NCT02831855, NCT00413699, NCT00147498, NCT00413660, NCT00550446, NCT00603512, NCT00687193, NCT00661661, NCT01164579, NCT00976599, NCT01059864, NCT01359150, NCT01262118, NCT01484561, NCT02281552, NCT02147587, NCT02092467.

Systemic complications of rheumatoid arthritis: Focus on pathogenesis and treatment

As a systemic autoimmune disease, rheumatoid arthritis (RA) usually causes damage not only to joints, but also to other tissues and organs including the heart, kidneys, lungs, digestive system, eyes, skin, and nervous system. Excessive complications are closely related to the prognosis of RA patients and even lead to increased mortality. This article summarizes the serious complications of RA, focusing on its incidence, pathogenesis, clinical features, and treatment methods, aiming to provide a reference for clinicians to better manage the complications of RA.

Interleukin-34-regulated T-cell responses in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease with a multifaceted etiology, which primarily affects and results in the deterioration of the synovium of patients. While the exact etiology of RA is still largely unknown, there is growing interest in the cytokine interleukin-34 (IL-34) as a driver or modulator of RA pathogenesis on the grounds that IL-34 is drastically increased in the serum and synovium of RA patients. Several studies have so far revealed the relationship between IL-34 levels and RA disease progression. Nevertheless, the significance and role of IL-34 in RA have remained ambiguous, as illustrated by two most recent studies, which reported contrasting effects of genetic IL-34 deletion in RA. Of note, IL-34 is a macrophage growth factor and is increasingly perceived as a master regulator of T-cell responses in RA via macrophage-dependent as well as T cell-intrinsic mechanisms. In this regard, several studies have demonstrated that IL-34 potentiates helper T-cell (Th) responses in RA, whereas studies also suggested that IL-34 alleviates synovial inflammation, potentially by inducing regulatory T-cells (Treg). Herein, we provide an overview of the current understanding of IL-34 involvement in RA and outline IL-34-mediated mechanisms in regulating T-cell responses in RA.

A Mini Review on Osteoporosis: From Biology to Pharmacological Management of Bone Loss

Osteoporosis refers to excessive bone loss as reflected by the deterioration of bone mass and microarchitecture, which compromises bone strength. It is a complex multifactorial endocrine disease. Its pathogenesis relies on the presence of several endogenous and exogenous risk factors, which skew the physiological bone remodelling to a more catabolic process that results in net bone loss. This review aims to provide an overview of osteoporosis from its biology, epidemiology and clinical aspects (detection and pharmacological management). The review will serve as an updated reference for readers to understand the basics of osteoporosis and take action to prevent and manage this disease.

The prevalence of osteoporosis in rheumatoid arthritis patient: a systematic review and meta-analysis

Osteoporosis (OP) is one of the most commonly known extra-articular complications of rheumatoid arthritis (RA). Since the prevalence of OP is diverse in different studies and there is no general consensus about it, in this systematic review, we aimed to investigate the global prevalence of OP among RA patients. In this review, three databases including Medline via PubMed, Scopus, and Web of Science (Clarivate analytics) were searched by various keywords. After screening of retrieved papers, the related data of included papers were extracted and analyzed. To assess the risk of methodological bias of included studies, quality assessment checklist for prevalence studies was used. Because of heterogeneity among studies, random-effect model was used to pooled the results of primary studies. In this review, the results of 57 studies were summarized and the total included sample size was 227,812 cases of RA with 64,290 cases of OP. The summary point prevalence of OP among RA was estimated as 27.6% (95%CI 23.9-31.3%). Despite significant advances in prevention, treatment and diagnostic methods in these patients, it still seems that the prevalence of OP in these patients is high and requires better and more timely interventions.

A Review of Signaling Transduction Mechanisms in Osteoclastogenesis Regulation by Autophagy, Inflammation, and Immunity

Osteoclastogenesis is an ongoing rigorous course that includes osteoclast precursors fusion and bone resorption executed by degradative enzymes. Osteoclastogenesis is controlled by endogenous signaling and/or regulators or affected by exogenous conditions and can also be controlled both internally and externally. More evidence indicates that autophagy, inflammation, and immunity are closely related to osteoclastogenesis and involve multiple intracellular organelles (e.g., lysosomes and autophagosomes) and certain inflammatory or immunological factors. Based on the literature on osteoclastogenesis induced by different regulatory aspects, emerging basic cross-studies have reported the emerging disquisitive orientation for osteoclast differentiation and function. In this review, we summarize the partial potential therapeutic targets for osteoclast differentiation and function, including the signaling pathways and various cellular processes.

Pathomechanisms of bone loss in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease, in which the inflammatory processes involve the skeletal system and there is marked destruction of the bones and the surrounding structures. In this review, we discuss the current concepts of osteoimmunology in RA, which represent the molecular crosstalk between the immune and skeletal systems, resulting in the disruption of bone remodeling. Bone loss in RA can be focal or generalized, leading to secondary osteoporosis. We have summarized the recent studies of bone loss in RA, which focused on the molecular aspects, such as cytokines, autoantibodies, receptor activator of nuclear kappa-β ligand (RANKL) and osteoprotegerin (OPG). Apart from the above molecules, the role of aryl hydrocarbon receptor (Ahr), which is a potential key mediator in this process through the generation of the Th17 cells, is discussed. Hence, this review highlights the key insights into molecular mechanisms of bone loss in RA.

A Review on the Molecular Mechanisms of Action of Natural Products in Preventing Bone Diseases

The drugs used for treating bone diseases (BDs), at present, elicit hazardous side effects that include certain types of cancers and strokes, hence the ongoing quest for the discovery of alternatives with little or no side effects. Natural products (NPs), mainly of plant origin, have shown compelling promise in the treatments of BDs, with little or no side effects. However, the paucity in knowledge of the mechanisms behind their activities on bone remodeling has remained a hindrance to NPs’ adoption. This review discusses the pathological development of some BDs, the NP-targeted components, and the actions exerted on bone remodeling signaling pathways (e.g., Receptor Activator of Nuclear Factor κ B-ligand (RANKL)/monocyte/macrophage colony-stimulating factor (M-CSF)/osteoprotegerin (OPG), mitogen-activated protein kinase (MAPK)s/c-Jun N-terminal kinase (JNK)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), Kelch-like ECH-associated protein 1 (Keap-1)/nuclear factor erythroid 2–related factor 2 (Nrf2)/Heme Oxygenase-1 (HO-1), Bone Morphogenetic Protein 2 (BMP2)-Wnt/β-catenin, PhosphatidylInositol 3-Kinase (PI3K)/protein kinase B (Akt)/Glycogen Synthase Kinase 3 Beta (GSK3β), and other signaling pathways). Although majority of the studies on the osteoprotective properties of NPs against BDs were conducted ex vivo and mostly on animals, the use of NPs for treating human BDs and the prospects for future development remain promising.

Wnt5a-Ror2 signaling mediates root resorption

INTRODUCTION

This study aimed to investigate the role of wingless-type MMTV integration site family member 5a (Wnt5a)-receptor tyrosine kinase-like orphan receptor 2 (Ror2) signaling in root resorption.

METHODS

The messenger RNA (mRNA) expression of Wnt5a, Ror2, and RANKL in periodontal ligament cells (PDLCs) under compression force (CF) with or without Ror2 small interfering RNA (siRNA) were measured by quantitative reverse transcription-polymerase chain reaction, and these proteins released into culture supernatants were measured using enzyme-linked immunosorbent assay. Then these PDLC-conditioned media under CF with or without Ror2 siRNA were used to culture osteoclast precursors to detect osteoclastogenesis effects via tartrate-resistant acid phosphatase staining. In in vivo studies, the odontoclast number and the root resorption volume under excessive CF with or without Ror2 siRNA were investigated by tartrate-resistant acid phosphatase immunohistochemical staining and microcomputed tomography. The protein levels for Wnt5a, Ror2, and receptor activator of nuclear factor-kappa B ligand (RANKL) in the periodontal ligament tissues were also detected using immunohistochemical staining. Finally, the odontoclast number, root resorption volume, and the mRNA and protein expressions were compared between immature and mature teeth.

RESULTS

The mRNA production and protein release level of Wnt5a, Ror2, and RANKL increased after CF, whereas they were significantly downregulated with Ror2 siRNA. The osteoclast number increased treating with culture medium from PDLC applying CF, but the increase was inhibited after adding Ror2 siRNA. In the animal model, the odontoclast number and root resorption volume significantly increased in the CF group but decreased in the CF with the Ror2 siRNA group. The protein levels of Wnt5a, Ror2, and RANKL in periodontal ligament were upregulated under excessive CF, and the pathway was inhibited with Ror2 siRNA. In the immature tooth group, the odontoclast number, root resorption volume, and the mRNA and protein expressions of Wnt5a-Ror2 signaling were reduced.

CONCLUSIONS

Wnt5a-Ror2 signaling in PDLCs enhanced by excessive CF could promote RANKL release and induce precursor differentiation, partly leading to increased odontoclast activity and ultimate root resorption. The less resorption of the immature tooth may be due to odontoclastogenesis inhibition by decreased expression of Wnt5a-Ror2 signaling.

Influence of Iguratimod on Bone Metabolism in Patients with Rheumatoid Arthritis: A Meta-analysis

Background

Influence of iguratimod on bone mineral density (BMD) and biomarkers of bone metabolism in patients with rheumatoid arthritis (RA) remains not determined. Accordingly, a meta-analysis was performed for systematical evaluation.

Methods

Relevant randomized controlled trials (RCTs) were retrieved by searching of PubMed, Embase, Cochrane's Library, China National Knowledge Infrastructure (CNKI), and Wanfang databases. A random-effect model was used to pool the results.

Results

In total, 24 RCTs including 2439 patients with RA contributed to the meta-analysis. Pooled results showed that compared to methotrexate alone, additional use of iguratimod 25 mg Bid for 12∼24 weeks significantly improved lumbar-spine BMD (mean difference [MD]: 0.12, 95% confidence interval [CI]: 0.04 to 0.20, p=0.002, I 2 = 39%) in patients with RA. Moreover, treatment with iguratimod was associated with increased serum osteoprotegerin (MD: 180.36 pg/ml, 95% CI: 122.52 to 238.20, p < 0.001, I 2 = 48%), and decreased serum receptor activator for nuclear factor kappa-B ligand (MD: -10.65 pmol/l, 95% CI: -15.59 to -5.72, p < 0.001, I 2 = 53%). In addition, iguratimod was associated with increased bone formation markers such as the serum N-terminal middle molecular fragment of osteocalcin (MD: 4.23 ng/ml, 95% CI: 3.74 to 4.71, p < 0.001, I 2 = 35%) and total procollagen type I amino-terminal propeptide (MD: 9.10 ng/ml, 95% CI: 7.39 to 10.80, p < 0.001, I 2 = 86%), but decreased the bone resorption marker such as serum β-C terminal cross-linking telopeptide of type 1 collagen (MD: -0.18 pg/ml, 95% CI: -0.21 to -0.14, p < 0.001, I 2 = 70%).

Conclusions

Iguratimod could prevent the bone loss and improve the bone metabolism in patients with RA.

Calycosin prevents bone loss induced by hindlimb unloading

Bone loss induced by microgravity exposure seriously endangers the astronauts' health, but its countermeasures still have certain limitations. The study aims to find potential protective drugs for the prevention of the microgravity-induced bone loss. Here, we utilized the network pharmacology approach to discover a natural compound calycosin by constructing the compound-target interaction network and analyzing the topological characteristics of the network. Furthermore, the hind limb unloading (HLU) rats' model was conducted to investigate the potential effects of calycosin in the prevention of bone loss induced by microgravity. The results indicated that calycosin treatment group significantly increased the bone mineral density (BMD), ameliorated the microstructure of femoral trabecular bone, the thickness of cortical bone and the biomechanical properties of the bone in rats, compared that in the HLU group. The analysis of bone turnover markers in serum showed that both the bone formation markers and bone resorption markers decreased after calycosin treatment. Moreover, we found that bone remodeling-related cytokines in serum including IFN-γ, IL-6, IL-8, IL-12, IL-4, IL-10 and TNF-α were partly recovered after calycosin treatment compared with HLU group. In conclusion, calycosin partly recovered hind limb unloading-induced bone loss through the regulation of bone remodeling. These results provided the evidence that calycosin might play an important role in maintaining bone mass in HLU rats, indicating its promising application in the treatment of bone loss induced by microgravity.

Osteoporosis in patients with rheumatoid arthritis is associated with serum immune regulatory cellular factors

OBJECTIVE

Osteoporosis (OP) is a comorbidity of rheumatoid arthritis (RA) that largely causes disability. This study discussed the expression patterns of serum immunoregulatory factors and their clinical significance in RA patients complicated with OP.

METHODS

A total of 116 RA patients were enrolled. Bone mineral density (BMD) was measured using dual energy X-ray absorptiometry to allocate patients to OP group (N = 62) and non-OP group (N = 54). CRP, rheumatoid factor, IgG, IgA, and IgM were detected using rate nephelometry. Erythrocyte sedimentation rate (ESR) and bone metabolic indexes were detected using Microsed automatic ESR analyzer and Cobas e601 automated immunoassay systems and reagents. IL-17, IL-6, TNF-α, IL-10, and IL-4 levels were determined using ELISA kit and their prediction values on OP were analyzed using the ROC curve. Influencing factors of OP incidence were analyzed using logistic regression model.

RESULTS

RA patients with OP showed increased age, disease course, tender and swollen joints, ESR, CRP, DAS28 scores, β-CTX, IL-17, IL-6, and TNF-α, and decreased 25(OH)D3, IL-10, and IL-4. DAS28 was positively correlated with IL-17, IL-6, and TNF-α, and negatively correlated with IL-10 and IL-4. DAS28, IL-17, IL-10, and IL-4 were independently correlated with OP in RA patients. The combination of DAS28, IL-17, IL-10, and IL-4 can better predict the incidence of OP complication in RA patients.

CONCLUSION

IL-17, IL-6, TNF-α, IL-10, and IL-4 were associated with disease activity of RA patients complicated with OP. A combination of DAS28, IL-17, IL-10, and IL-4 might predict OP incidence in RA patients.

Abnormalities of Peripheral Lymphocyte Subsets in Rheumatoid Arthritis Patients Complicated with Osteoporosis

Introduction

Osteoporosis (OP) is one of the major comorbidities of rheumatoid arthritis (RA). Recent studies have shown that immune cells modulate bone health and regulate bone remodeling. However, the alterations of lymphocyte subsets in RA patients with OP are unclear. Here, we assessed the absolute numbers and proportions of the subsets in RA sufferers with OP and investigated the clinical significance.

Methods

A total of 777 RA patients and 117 gender- and age-matched healthy controls (HCs) were enrolled in this study. Patients were divided into RA-non-OP and RA-OP group according to their bone mineral density (BMD) and the history of fragility fracture. Peripheral lymphocyte subsets of participants were assessed by flow cytometry.

Results

Among 220 (28.31%) RA-OP patients, there were higher levels of erythrocyte sedimentation rate (ESR) (P = 0.011), C-reactive protein (CRP) (P = 0.028), rheumatoid factor (RF) (P = 0.013) and anti-cyclic citrullinated peptide antibody (ACPA) (P = 0.010), while red blood cells (RBC) (P = 0.039) were lower than those in RA-non-OP group. Compared with those of HCs and RA-non-OP group, the level of circulating Th17 cells in RA-OP patients was significantly increased (P < 0.05), while those of Tregs decreased (P < 0.01), leading to a higher ratio of Th17/Treg (P < 0.01). Notably, the level of B cells in both RA-non-OP and RA-OP group was reduced, this alteration was more obvious in patients with OP (P < 0.05).

Conclusions

Immune disorders characterized by peripheral Th17/Treg imbalance and reduced B cells may contribute directly or indirectly to OP in RA, and this deserves more clinical attention.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40744-022-00452-x.

The Dynamic Feature of Macrophage M1/M2 Imbalance Facilitates the Progression of Non-Traumatic Osteonecrosis of the Femoral Head

Non-traumatic osteonecrosis of the femoral head (NONFH) remains a common refractory disease with poorly understood pathogenesis. Macrophage M1/M2 imbalance and chronic inflammatory microenvironment have been suggested to be closely related to osteonecrosis. Here we describe direct visual evidence for the involvement of dynamic changes in macrophages and the chronic inflammatory microenvironment in human NONFH. Osteonecrosis induces inflammatory responses and macrophage enrichment in the reparative area, and the number of inflammatory cells and macrophages falls during progressive-to end-stage NONFH. Multiplex immunohistochemistry demonstrated that macrophage M1/M2 ratio increased from 3 to 10 during progressive-to end-stage. During the progressive-stage, new blood vessels formed in the reparative area, M2 macrophages accumulated in perivascular (M1/M2 ratio ∼0.05), while M1 macrophages were enriched in avascular areas (M1/M2 ratio ∼12). Furthermore, inflammatory cytokines were detected in synovial fluid and plasma using cytometric bead arrays. Interleukin (IL)-6 and IL-1β were persistently enriched in synovial fluid compared to plasma in patients with NONFH, and this difference was confirmed by immunohistochemistry staining. However, only IL-6 levels in plasma were higher in patients with progressive-stage NONFH than in osteoarthritis. Moreover, fibrosis tissues were observed in the necrotic area in progressive-stage and end-stage NONFH based on Sirius Red staining. Together, these findings indicate that macrophage M1/M2 imbalance facilitates the progression of NONFH, a chronic inflammatory disease characterized by chronic inflammation, osteonecrosis and tissue fibrosis in the local lesion. Inhibiting inflammation, promoting the resolution of inflammation, switching macrophages to an M2 phenotype, or inhibiting their adoption of an M1 phenotype may be useful therapeutic strategies against NONFH.

First metatarsophalangeal joint arthrodesis/fusion: a systematic review of modern fixation techniques

Background

First metatarsophalangeal joint arthrodesis is commonly performed for symptomatic end-stage hallux rigidus. It has been postulated to produce good results in the literature. Various fixation techniques offer differences in union rates, complications and functional outcomes, stirring debates about which produces the best outcomes for patients. Therefore, this review aims to synthesise and compare the outcomes of modern fixation techniques used for first metatarsophalangeal joint (FMPJ) arthrodesis.

Methods

The electronic database searched were PubMed, CINAHL, Cochrane Library, and Google Scholar. The critical appraisal skills programme tool for cohort study was used. The interventions consisted of screw(s), plate(s), and staple(s). Studies comprising outdated fixation techniques such as suture, metallic wire, external fixation, Rush rods or Steinmann pins were excluded. Participants were adults over 18 years, undergoing FMPJ arthrodesis in the UK. Studies with the population consisting primarily of revision cases, patients with rheumatoid arthritis or diabetes were excluded.

Results

Seven UK studies included 277 feet and a 95.7% overall union rate at a mean union time of 83.5 days. Staples had the highest union rate of 98.2% at mean union time of 84 days, followed by plates (95.2%, 92 days), and finally screws (94.9%, 71 days). The overall complication incidence is 5.8%. All of the fixation techniques produced good functional outcomes postoperatively.

Conclusions

Whilst staple techniques showed the highest union rate, plating techniques are preferable over screws or staples for better results across several outcome measures, including reduced complication incidence, stability, early ambulation, and good functional outcome. The Manchester-Oxford Foot Questionnaire and EuroQol-5Dimensional are recommended as measurement tools to assess functional outcomes following FMPJ arthrodesis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13047-022-00540-9.

Machine Learning Algorithms: Prediction and Feature Selection for Clinical Refracture after Surgically Treated Fragility Fracture

BACKGROUND

The number of patients with fragility fracture has been increasing. Although the increasing number of patients with fragility fracture increased the rate of fracture (refracture), the causes of refracture are multifactorial, and its predictors are still not clarified. In this issue, we collected a registry-based longitudinal dataset that contained more than 7000 patients with fragility fractures treated surgically to detect potential predictors for clinical refracture.

METHODS

Based on the fact that machine learning algorithms are often used for the analysis of a large-scale dataset, we developed automatic prediction models and clarified the relevant features for patients with clinical refracture. Formats of input data containing perioperative clinical information were table data. Clinical refracture was documented as the primary outcome if the diagnosis of fracture was made at postoperative outpatient care. A decision-tree-based model, LightGBM, had moderate accuracy for the prediction in the test and the independent dataset, whereas the other models had poor accuracy or worse.

RESULTS

From a clinical perspective, rheumatoid arthritis (RA) and chronic kidney disease (CKD) were noted as the relevant features for patients with clinical refracture, both of which were associated with secondary osteoporosis.

CONCLUSION

The decision-tree-based algorithm showed the precise prediction of clinical refracture, in which RA and CKD were detected as the potential predictors. Understanding these predictors may improve the management of patients with fragility fractures.

miR‑148a‑3p facilitates osteogenic differentiation of fibroblasts in ankylosing spondylitis by activating the Wnt pathway and targeting DKK1

Ankylosing spondylitis (AS) is a chronic inflammatory form of arthritis. MicroRNAs (miRNAs) have been identified to serve as therapeutic targets in various inflammatory diseases. The aim of the present study was to determine the functional mechanism of miR-148a-3p on AS. Specimens were collected from AS patients and non-AS patients. Fibroblasts were delivered with the aid of miR-148a-3p inhibitor. Cell staining was performed to observe the morphological changes, calcified nodules, and mineralization degree. The binding sites of miR-148a-3p and DKK1 were predicted on the Starbase website and subsequently verified by means of dual-luciferase reporter assay. AS fibroblasts with silenced miR-148a-3p were transfected with si-DKK1. Levels of RUNX2 and Osteocalcin, DKK1 and Wnt1 protein and phosphorylation level of β-catenin were detected by means of western blot analysis. Results of the present study denoted that AS upregulated miR-148a-3p in fibroblasts to exacerbate osteogenic differentiation, resulting in increased calcified nodules and mineralization degree. Silencing miR-148a-3p could reverse the upregulation of RUNX2 and Osteocalcin in AS fibroblasts and reduce the calcified nodules and mineralization degree. miR-148a-3p targeted DKK1. DKK1 knockdown averted the effect of silencing miR-148a-3p in AS fibroblasts. In addition, silencing miR-148a-3p reversed the upregulation of Wnt1 and β-catenin proteins in AS fibroblasts. To conclude, miR-148a-3p exacerbated the osteogenic differentiation of AS fibroblasts by inhibiting DKK1 expression and activating the Wnt pathway.

Periodontal Disease Augments Cardiovascular Disease Risk Biomarkers in Rheumatoid Arthritis

Objectives: Periodontal disease (PD) and rheumatoid arthritis (RA) are known chronic conditions with sustained inflammation leading to osteolysis. Cardiovascular diseases (CVD) are frequent comorbidities that may arise from sustained inflammation associated with both PD and RA. In order to determine CVD risk, alterations at the molecular level need to be identified. The objective of this study, therefore, was to assess the relationship of CVD associated biomarkers in RA patients and how it is influenced by PD. Methods: The study consisted of patient (26 RA with PD, 21 RA without PD, 51 patients with PD only) and systemically and periodontally healthy control (n = 20) groups. Periodontal parameters bleeding on probing, probing pocket depth, and marginal bone loss were determined to characterize the patient groups. Proteomic analysis of 92 CVD-related protein biomarkers was performed using a multiplex proximity extension assay. Biomarkers were clustered using the search tool for retrieval of interacting genes (STRING) to determine protein−protein interaction (PPI) networks. Results: RA patients with PD had higher detection levels for 47% of the measured markers (ANGPT1, BOC, CCL17, CCL3, CD4, CD84, CTRC, FGF-21, FGF-23, GLO1, HAOX1, HB-EGF, hOSCAR, HSP 27, IL16, IL-17D, IL18, IL-27, IL6, LEP, LPL, MERTK, MMP12, MMP7, NEMO, PAPPA, PAR-1, PARP-1, PD-L2, PGF, PIgR, PRELP, RAGE, SCF, SLAMF7, SRC, THBS2, THPO, TNFRSF13B, TRAIL-R2, VEGFD, VSIG2, and XCL1) as compared to RA without PD. Furthermore, a strong biological network was identified amongst these proteins (clustering coefficient = 0.52, PPI enrichment p-value < 0.0001). Coefficients for protein clusters involved in CVD (0.59), metabolic (0.53), and skeletal (0.51) diseases were strongest in the PD group. Conclusion: Periodontal disease augments CVD-related biomarkers in RA through shared pathological clusters, concurrently enhancing metabolic and skeletal disease protein interactions, independent of autoimmune status.

Drug Investigation to Dampen the Comorbidity of Rheumatoid Arthritis and Osteoporosis via Molecular Docking Test

At present, most rheumatoid arthritis (RA) patients are at risk of osteoporosis (OP), which is increased by 1.5 times compared to non-RA individuals. Hence, we investigated overlapping targets related directly to the occurrence and development of RA and OP through public databases (DisGeNET, and OMIM) and literature. A total of 678 overlapping targets were considered as comorbid factors, and 604 out of 678 were correlated with one another. Interleukin 6 (IL-6), with the highest degree of value in terms of protein−protein interaction (PPI), was considered to be a core target against comorbidity. We identified 31 existing small molecules (< 1000 g/mol) as IL-6 inhibitors, and 19 ligands were selected by the 3 primary criteria (Lipinski’s rule, TPSA, and binding energy). We postulated that MD2-TLR4-IN-1 (PubChem ID: 138454798), as confirmed by the three criteria, was the key ligand to alleviate comorbidity between RA and OP. In conclusion, we described a promising active ligand (MD2-TLR4-IN-1), and a potential target (IL-6) against comorbidity of RA and OP, providing scientific evidence for a further clinical trial.

Protective effect of methyl gallate on murine antigen-induced arthritis by inhibiting inflammatory process and bone erosion

Methyl gallate (MG) is a plant-derived phenolic compound known to present remarkable anti-inflammatory effect in different experimental models, such as paw oedema, pleurisy, zymosan-induced arthritis and colitis. Herein we investigated the effect of MG in the mice model of antigen-induced arthritis (AIA), a model with complex inflammatory response, driven primally by immune process and that cause bone and cartilage erosion similarly found in rheumatoid arthritis. Arthritis was induced by intra-articular injection of albumin methylated from bovine serum (mBSA) in C57BL/6 male mice previously immunized. The dose-response analysis of MG (0.7-70 mg/kg; p.o) showed that maximum inhibition was reached with the dose of 7 mg/kg on paw oedema and cell infiltration induced by AIA at 7 h. Treatment with MG (7 mg/kg; p.o) or with the positive control, dexamethasone (Dexa, 10 mg/kg, ip) reduced AIA oedema formation, leukocyte infiltration, release of extracellular DNA and cytokine production 7 and 24 h (acute response). Mice treated daily with MG for 7 days showed no significant weight loss or liver and kidney toxicity contrary to dexamethasone that induced some degree of toxicity. Prolonged treatment with MG inhibited the late inflammatory response (28 days) reducing oedema formation, cell infiltration, synovial hyperplasia, pannus formation and cartilage degradation as observed in histopathological analyses. Ultimately, MG reduced bone resorption as evidenced by a decrease in tartrate-resistant acid phosphate (TRAP)-positive cells number in femur histology. Altogether, we demonstrate that MG ameliorates the inflammatory reaction driven primarily by the immune process, suggesting a potential therapeutic application in arthritis treatment.

Sarcopenia May Be a Risk Factor for Osteoporosis in Chinese Patients with Rheumatoid Arthritis

Purpose

Osteoporosis (OP) has been classically considered a co-morbidity of rheumatoid arthritis (RA). This investigation determined the clinical significance of sarcopenia in patients with RA combined with OP or whether sarcopenia influences RA when combined with OP.

Materials and Methods

Data pertaining to the duration of RA, C-reactive protein (CRP) level, and erythrocyte sedimentation rate (ESR) were collected from 549 RA cases and 158 healthy individuals. Disease activity score at 28 joints (DAS28), the body mass index (BMI), health assessment questionnaire (HAQ), bone mineral density (BMD), and Sharp score were compared between the 2 groups.

Results

The prevalence of OP (33.3% vs 12.7%, χ²= 69.992, P < 0.0001) and sarcopenia (61.7% vs 9.0%, χ²= 135.336, P < 0.01) was greater in patients with RA than in healthy controls. RA patients with sarcopenia had a higher incidence of OP at all measured sites than RA patients without sarcopenia (all P < 0.0001), and the incidence of OP was significantly higher than in patients with mild-to-moderate or severe RA without sarcopenia (P < 0.0001). Differences in age, gender, course of disease, CRP level, ESR, DAS28, BMI, HAQ, BMD, and Sharp score were statistically different between the RA with or without sarcopenia groups (P < 0.01). The incidence of OP and sarcopenia was higher in RA patients treated than not treated with glucocorticoids [GCs] (36.4% vs 29.3%, P < 0.05 and 66.1% vs 56.0%, respectively; P < 0.05). Logistic regression showed that the risk factors for OP in RA individuals were female (OR, 14.671; 95% CI, 6.877–31.300; P < 0.0001), age (OR, 1.100; 95% CI, 1.076–1.124; P < 0.0001), and sarcopenia (OR, 3.561; 95% CI, 2.214–5.726; P < 0.0001).

Conclusion

OP and sarcopenia are common in RA patients. Sarcopenia may be a risk factor for OP occurrence in Chinese patients with RA.