Biomarkers of Bone Metabolism in Ankylosing Spondylitis in Relation to Osteoproliferation and Osteoporosis

The Role of Sclerostin in Rheumatic Diseases: A Review

Systemic connective tissue disorders constitute a heterogenous group of autoimmune diseases with the potential to affect a range of organs. Rheumatoid arthritis (RA) is a chronic, progressive, autoimmune inflammatory disease affecting the joints. Systemic lupus erythematosus (SLE) may manifest with multiple system involvement as a result of inflammatory response to autoantibodies. Spondyloarthropathies (SpAs) such as ankylosing spondylitis (AS) or psoriatic arthritis (PsA) are diseases characterised by the inflammation of spinal joints, paraspinal tissues, peripheral joints and enthesitis as well as inflammatory changes in many other systems and organs. Physiologically, sclerostin helps to maintain balance in bone tissue metabolism through the Wnt/β-catenin pathway, which represents a major intracellular signalling pathway. This review article aims to present the current knowledge on the role of sclerostin in the Wnt/β-catenin pathway and its correlation with clinical data from RA, SLE, AS and PsA patients.

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.

Quantitative proteomic screening uncovers candidate diagnostic and monitoring serum biomarkers of ankylosing spondylitis

BACKGROUND

We sought to discover serum biomarkers of ankylosing spondylitis (AS) for diagnosis and monitoring disease activity.

METHODS

We studied biologic-treatment-naïve AS and healthy control (HC) patients' sera. Eighty samples matched by age, gender, and race (1:1:1 ratio) for AS patients with active disease, inactive disease, and HC were analyzed with SOMAscan™, an aptamer-based discovery platform. T-tests tests were performed for high/low-disease activity AS patients versus HCs (diagnosis) and high versus low disease activity (Monitoring) in a 2:1 and 1:1 ratio, respectively, to identify differentially expressed proteins (DEPs). We used the Cytoscape Molecular Complex Detection (MCODE) plugin to find clusters in protein-protein interaction networks and Ingenuity Pathway Analysis (IPA) for upstream regulators. Lasso regression analysis was performed for diagnosis.

RESULTS

Of the 1317 proteins detected in our diagnosis and monitoring analyses, 367 and 167 (317 and 59, FDR-corrected q < .05) DEPs, respectively, were detected. MCODE identified complement, IL-10 signaling, and immune/interleukin signaling as the top 3 diagnosis PPI clusters. Complement, extracellular matrix organization/proteoglycans, and MAPK/RAS signaling were the top 3 monitoring PPI clusters. IPA showed interleukin 23/17 (interleukin 22, interleukin 23A), TNF (TNF receptor-associated factor 3), cGAS-STING (cyclic GMP-AMP synthase, Stimulator of Interferon Gene 1), and Jak/Stat (Signal transducer and activator of transcription 1), signaling in predicted upstream regulators. Lasso regression identified a Diagnostic 13-protein model predictive of AS. This model had a sensitivity of 0.75, specificity of 0.90, a kappa of 0.59, and overall accuracy of 0.80 (95% CI: 0.61-0.92). The AS vs HC ROC curve was 0.79 (95% CI: 0.61-0.96).

CONCLUSION

We identified multiple candidate AS diagnostic and disease activity monitoring serum biomarkers using a comprehensive proteomic screen. Enrichment analysis identified key pathways in AS diagnosis and monitoring. Lasso regression identified a multi-protein panel with modest predictive ability.

MEG3 alleviates ankylosing spondylitis by suppressing osteogenic differentiation of mesenchymal stem cells through regulating microRNA-125a-5p-mediated TNFAIP3

Osteoblasts are important regulators of bone formation, but their roles in ankylosing spondylitis (AS) remain unclear. This study aims to explore the role of long non-coding RNA (lncRNA) maternally expressed 3 (MEG3) MEG3 in AS. Serum from AS patients as well as AS mesenchymal stem cells (ASMSCs) and healthy donors mesenchymal stem cells (HDMSCs) was collected. Accordingly, poorly expressed MEG3 and TNF alpha induced protein 3 (TNFAIP3) as well as overexpressed microRNA-125a-5p (miR-125a-5p) were noted in the serum of AS patients and in ASMSCs during the osteogenic induction process. Meanwhile, the interaction among MEG3, miR-125a-5p, and TNFAIP3 was determined and their effect on osteoblast activity was examined in vitro and in vivo. Overexpression of MEG3 and TNFAIP3 or inhibition of miR-125a-5p was found to inactivate the Wnt/β-catenin pathway, thus suppressing osteogenic differentiation of MSCs. MEG3 competitively bound to miR-125a-5p to increase TNFAIP3 expression, thereby inactivating the Wnt/β-catenin pathway and repressing the osteogenic differentiation of MSCs. In proteoglycan (PG)-induced AS mouse models, MEG3 also reduced osteogenic activity of MSCs to inhibit AS progression through the miR-125a-5p/TNFAIP3/Wnt/β-catenin axis. Therefore, up-regulation of MEG3 or depletion of miR-125a-5p holds potential of alleviating AS, which sheds light on a new therapeutic strategy for AS treatment.

Periostin: an emerging activator of multiple signaling pathways

Matricellular proteins are responsible for regulating the microenvironment, the behaviors of surrounding cells, and the homeostasis of tissues. Periostin (POSTN), a non-structural matricellular protein, can bind to many extracellular matrix proteins through its different domains. POSTN usually presents at low levels in most adult tissues but is highly expressed in pathological sites such as in tumors and inflamed organs. POSTN can bind to diverse integrins to interact with multiple signaling pathways within cells, which is one of its core biological functions. Increasing evidence shows that POSTN can activate the TGF-β, the PI3K/Akt, the Wnt, the RhoA/ROCK, the NF-κB, the MAPK and the JAK pathways to promote the occurrence and development of many diseases, especially cancer and inflammatory diseases. Furthermore, POSTN can interact with some pathways in an upstream and downstream relationship, forming complicated crosstalk. This article focuses on the interactions between POSTN and different signaling pathways in diverse diseases, attempting to explain the mechanisms of interaction and provide novel guidelines for the development of targeted therapies.

Practical Significance of Biomarkers in Axial Spondyloarthritis: Updates on Diagnosis, Disease Activity, and Prognosis

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that can lead to ankylosis by secondary ossification of inflammatory lesions, with progressive disability and a significant impact on quality of life. It is also a risk factor for the occurrence of comorbidities, especially cardiovascular diseases (CVDs), mood disorders, osteoporosis, and malignancies. Early diagnosis and treatment are needed to prevent or decrease functional decline and to improve the patient's prognosis. In respect of axSpA, there is an unmet need for biomarkers that can help to diagnose the disease, define disease activity and prognosis, and establish personalized treatment approaches. The aim of this review was to summarize the available information regarding the most promising biomarkers for axSpA. We classified and identified six core categories of biomarkers: (i) systemic markers of inflammation; (ii) molecules involved in bone homeostasis; (iii) HLA-B27 and newer genetic biomarkers; (iv) antibody-based biomarkers; (v) microbiome biomarkers; and (vi) miscellaneous biomarkers. Unfortunately, despite efforts to validate new biomarkers, few of them are used in clinical practice; however, we believe that these studies provide useful data that could aid in better disease management.

Bone Involvement in Patients with Spondyloarthropathies

Spondyloarthropathies (SpA) are common systemic inflammatory rheumatic diseases, in which, as in other rheumatic diseases, levels of markers of bone resorption are elevated, leading to bone loss and elevated risk of vertebral fractures. However, the diseases are also associated with new bone formation in the spine, the so-called syndesmophytes. We tried to unravel the pathogenesis of formation and growth of syndesmophytes and evaluated new diagnostic and treatment options. After a successful meeting of the Working Group on Rheumatic Diseases at the ECTS 2020, we (WL and CR) were excited about the quality of the speakers (CM, JH, AG, and GL) and their complimentary lectures. Given the relative lack of reviews on spondyloarthropathies and bone, we decided to work together on a comprehensive review that might be interesting for basic scientists and clinically relevant for clinicians. Radiographic progression in axSpA is linked to several risk factors, like male sex, smoking, HLA-B-27, increased levels of CRP, presence of syndesmophytes, and marked inflammation on MRI. The potential role of mechanical stress in the context of physically demanding jobs has been also suggested to promote structural damages. Different treatment options from NSAIDs to biologic agents like TNF inhibitors (TNFi) or IL-17inhibitors (IL-17i) result in a reduction of inflammation and symptoms. However, all these different treatment options failed to show clear and reproducible results on inhibition on syndesmophyte formation. The majority of data are available on TNFi, and some studies suggested an effect in subgroups of patients with ankylosing spondylitis. Less information is available on NSAIDs and IL-17i. Since IL-17i have been introduced quite recently, more studies are expected. IL-17 inhibitors (Il-17i) potently reduce signs and symptoms, but serum level of IL-17 is not elevated, therefore, IL-17 probably has mainly a local effect. The failure of anti-IL-23 in axSpA suggests that IL-17A production could be independent from IL-23. It may be upregulated by TNFα, resulting in lower expression of DKK1 and RANKL and an increase in osteogenesis. In active AS markers of bone resorption are increased, while bone formation markers can be increased or decreased. Bone Turnover markers and additional markers related to Wnt such as DKK1, sclerostin, and RANKL are valuable for elucidating bone metabolism on a group level and they are not (yet) able to predict individual patient outcomes. The gold standard for detection of structural lesions in clinical practice is the use of conventional radiographics. However, the resolution is low compared to the change over time and the interval for detecting changes are 2 years or more. Modern techniques offer substantial advantages such as the early detection of bone marrow edema with MRI, the fivefold increased detection rate of new or growing syndesmophytes with low-dose CT, and the decrease in 18F-fluoride uptake during treatment with TNFα-inhibitors (TNFi) in a pilot study in 12 AS patients. Detection of bone involvement by new techniques, such as low-dose CT, MRI and 18-Fluoride PET-scans, and bone turnover markers, in combination with focusing on high-risk groups such as patients with early disease, elevated CRP, syndesmophytes at baseline, male patients and patients with HLA-B27 + are promising options for the near future. However, for optimal prevention of formation of syndesmophytes we need more detailed insight in the pathogenesis of bone formation in axSpA and probably more targeted therapies.

Does the thoracolumbar kyphosis secondary to ankylosing spondylitis affect the iliac trajectory of S2AI screw?

Background

The study aimed to evaluate the influence of thoracolumbar kyphosis secondary to ankylosing spondylitis (AS) on parameters of S2AI trajectory and to compare the ideal S2AI trajectory with those of the non-deformity patients with AS, sagittal deformity patients without AS, and the normal population reported in literatures.

Methods

Sagittal parameters including global kyphosis (GK), pelvic tilt (PT) and sacral slope (SS) were measured. Besides, according to the simulated ideal S2AI trajectory on the CT images, trajectory parameters were measured including Sag angle, Tsv angle, Max-length, Sacral distance and Iliac width. Starting-point parameters were also measured including PSIS distance, Skin distance, Iliac wing and S2 midline.

Results

Ninety-four AS-related thoracolumbar kyphosis patients were included. After adjusting the age and gender, twenty non-deformity patients with AS and 20 sagittal deformity patients without AS were selected to compare with patients with AS-related thoracolumbar kyphosis, respectively. Sag angle in deformity patients with AS was smaller than other two groups (P < 0.001). No difference was found in Tsv angle and Sacral distance between AS patients with and without deformity. However, these two parameters were shown significant differences between deformity patients with AS and without AS. In deformity patients with AS, no significant differences were found in all parameters between genders Furthermore, there were strong correlations between PT and the bilateral Sag angle (P < 0.001).

Conclusions

The thoracolumbar kyphosis secondary to AS affects the Sag angle of the ideal S2AI trajectory which was approximately 20° smaller than that in non-deformity patients with AS, sagittal deformity patients without AS, and the normal population. Additionally, the Tsv angle and the Sacral distance in AS patients with thoracolumbar kyphosis were about 10° and 10 mm larger than those in sagittal deformity patients without AS, and the normal population reported in literatures.

Effects of secukinumab on bone mineral density and bone turnover biomarkers in patients with ankylosing spondylitis: 2-year data from a phase 3 study, MEASURE 1

Background

Axial spondyloarthritis including ankylosing spondylitis (AS) is characterized by chronic inflammation and new bone formation in the axial skeleton. On the other hand, bone loss, osteoporosis and an increased risk of vertebral fractures is known to frequently occur in AS. In the MEASURE 1 study, the clinically efficacious interleukin-17A inhibitor secukinumab was shown to have limited radiographic progression through 4 years in patients with active AS. Here we present a post hoc analysis to evaluate the effect of secukinumab on bone mineral density (BMD) and bone turnover biomarkers over 2 years in this study.

Methods

BMD was measured by dual-energy X-ray absorptiometry at the lumbar spine, total hip, and femoral neck. Spinal radiographs performed at baseline and Week 104 were assessed by modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) and analyzed in relation to BMD change, considering baseline syndesmophytes. Bone turnover biomarkers were assessed at baseline and at Weeks 52 or 104.

Results

Among 104 patients included in this analysis, 66% were male, with a mean (SD) age of 40.4 (12.3) years. In postmenopausal women and men ≥50 years of age (T-score), the proportion of patients having normal BMD at baseline and Week 104 were 54.5%/54.5% (lumbar spine), 31.6%/55.6% (total hip), and 42.1%/44.4% (femoral neck). Similarly, at baseline, the proportion of patients with osteopenia/osteoporosis was 31.8%/13.6% (lumbar spine), 57.9%/10.5% (total hip), 42.1%/15.8% (femoral neck), and 36.4%/9.1% (lumbar spine), 44.4%/0% (total hip) and 55.6%/0% (femoral neck) at Week 104, respectively. In premenopausal women and men < 50 years of age (Z-score), the proportion of patients having BMD below the expected range for age at baseline and Week 104 were 25.0%/21.2% (lumbar spine), 11.3%/17.8% (total hip), and 9.9%/8.9% (femoral neck). In relation to mSASSS change scores ≥2 over 2 years, the increase in lumbar spine BMD was not related to radiographic progression and syndesmophyte formation. No significant changes were observed in the bone turnover markers over time.

Conclusion

The high proportion of AS patients with diminished BMD was confirmed in this study. An increase of BMD in the lumbar spine after 2 years of secukinumab treatment in patients with AS was found that was probably unrelated to radiographic progression. No relevant effects of secukinumab on bone turnover biomarkers were documented.

Trial registration

MEASURE 1 (post hoc analysis) Clinicaltrials.gov, NCT01358175; Registered, 23 May 2011.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04930-1.

WNT16 elevation induced cell senescence of osteoblasts in ankylosing spondylitis

BACKGROUND

WNT16 is critical for bone homeostasis, but the effect of WNT16 in ankylosing spondylitis (AS) is still unknown. Here, we investigated whether WNT16 influences bone formation and pathophysiological changes of AS in an in vitro model.

METHODS

The bone tissue from the facet joints was obtained from seven disease control and seven AS patients. Primary osteoprogenitor cells of the facet joints were isolated using an outgrowth method. Isolated osteoprogenitor cells from both control and AS tissues were analyzed by microarray, RT-qPCR, immunoblotting, and immunohistochemistry. The bone-forming activity of osteoprogenitor cells was assessed by various in vitro assays. β-galactosidase staining and senescence-associated secretory phenotype (SASP) using RT-qPCR were used to assess cell senescence.

RESULTS

In microarray analysis, WNT16 expression was significantly elevated in AS osteoprogenitor cells compared to the control. We also validated that WNT16 expression was elevated in AS-osteoprogenitor cells and human AS-bone tissues. WNT16 treatment inhibited bone formation in AS-osteoprogenitor cells but not in the control. Intriguingly, AS-osteoprogenitor cells were stained markedly with β-galactosidase for cell senescence in WNT16 treatment. Furthermore, in an H2O2 stress-induced premature senescence condition, WNT16 treatment increased cell senescence in AS-osteoprogenitor cells and WNT16 treatment under the H2O2 stress condition showed an increase in p21 protein and SASP mRNA expression. The WNT16-induced SASP expression in AS-osteoprogenitor cells was reduced in WNT16 knockdown cultures.

CONCLUSION

WNT16 is highly expressed in AS and WNT16 treatment facilitated cell senescence in AS-osteoprogenitor cells during osteoblast differentiation accompanied by suppression of bone formation. The identified role of WNT16 in AS could influence bone loss in AS patients.

Serum RANKL levels in Chinese patients with ankylosing spondylitis: a meta-analysis

Objective

We aimed to determine the association between serum receptor activator of nuclear factor-kappa B ligand (sRANKL) levels and ankylosing spondylitis (AS) in Chinese patients.

Methods

The PubMed, Cochrane Library, Embase, Chinese Biomedical Database, Web of Science, China National Knowledge Infrastructure, VIP, and Wan Fang databases were searched for studies conducted before October 1, 2020, without language restrictions. STATA version 12.0 and Revman version 5.3 were used to analyze the data. The standard mean differences (SMDs) and corresponding 95% confidence intervals (95% CIs) were calculated.

Results

Twelve clinical case–control studies, including 585 patients with AS and 423 healthy controls, were included. The combined SMD for sRANKL suggested that the sRANKL level was significantly higher in Chinese patients with AS than in healthy controls (SMD: 3.27, 95% CI 2.11–4.43, P < 0.00001). Serum RANKL-related factor osteoprotegerin (OPG) levels (SMD: 0.86, 95% CI 0.09–1.64, P < 0.03) were lower in the Chinese patients with AS than in healthy controls, and the RANKL/OPG ratio (SMD = 1.05, 95% CI 0.64–1.46, P < 0.00001) in Chinese patients with AS was approximately the same as that of healthy controls. Subgroup analysis indicated that patients from North and South China had higher sRANKL levels than controls; the sRANKL levels of patients from South China were higher in the subgroup with a Bath Ankylosing Spondylitis Functional Index (BASFI) of > 4 than those of patients in other subgroups. In terms of duration, patients with AS for > 8 years had higher sRANKL levels than health controls. Other subgroup analyses were conducted by region, language, source of control, age, and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). In these subgroups, the sRANKL levels were significantly higher in the patients with AS than in healthy controls. The BASFI and BASDAI were sources of heterogeneity.

Conclusions

The sRANKL levels are higher in Chinese patients with AS, especially among those from South China. sRANKL levels may be positively correlated with the pathogenesis of AS among Chinese patients.

Relationship between smoking, clinical, inflammatory, and radiographic parameters in patients with ankylosing spondylitis

Background

Ankylosing spondylitis (AS) is an autoimmune multisystemic disease that attacks the spine, sacroiliacs, and often causes asymmetrical peripheral oligoarthritis. It results from the interaction between the genetic factors mainly Human Leukocyte Antigen B27 (HLA B27) and environmental factors. Current smoking has been reported to be a major risk factor for the incidence and progression of ankylosing spondylitis. So, we aim to explore the relationship between smoking and each of the clinical, inflammatory markers, functional limitation, and radiographic progression in ankylosing spondylitis patients.

Results

Fifty ankylosing spondylitis patients were included in this study. Comparisons of clinical data, radiographic, and inflammatory markers among smokers and nonsmokers revealed that AS current smokers showed a statistically significant decrease in chest expansion, increase in the occiput to wall distance (p < 0.001**), higher inflammatory marker, higher disease activity indices (Ankylosing Spondylitis Disease Activity Score, Bath Ankylosing Spondylitis Disease Activity Index), higher Bath Ankylosing Spondylitis functional index, and modified Stoke Ankylosing Spondylitis Spine Score than nonsmokers (P < 0.001**). The smoking index was positively correlated with BASFI, ASDAS, (mSASSS) (r = 0.584, p = 0.005*) and negatively correlated with chest expansion.

Conclusions

Current smoking in ankylosing spondylitis patients is associated with higher disease activity, inflammatory markers, functional disability, and radiological progression. This may add to the disease burden and thus interferes with the personal daily activities, physical mobility, life quality, and the response to TNFi therapy. So, stopping smoking is a mandatory step in controlling the disease activity and having favorable outcome.

Changes in bone formation regulator biomarkers in early axial spondyloarthritis

OBJECTIVE

The hallmark of advanced axial SpA (axSpA) is spine ankylosis due to excessive ectopic bone formation. This prospective study aimed to describe the changes in serum levels of different regulators [sclerostin, dickkopf-1 (DKK-1)] and markers of bone formation [bone morphogenetic protein 7 (BMP-7)] over 5 years in early axSpA patients and to assess determinants of such changes.

METHODS

The DEvenir des Spondyloarthropathies Indifférenciées Récentes cohort is a prospective, multicentre French study of 708 patients with early (>3 months-<3 years) inflammatory back pain suggestive of axSpA. Serum levels of BMP-7, sclerostin and DKK-1 were assessed at baseline and after 2 and 5 years. Changes in bone formation regulators over time were analysed using mixed linear models.

RESULTS

Serum BMP-7 significantly increased over time, with a median relative change of 223.7% [interquartile range (IQR) 0-10 700 (0.17 pg/ml/month), P < 0.001]. Serum sclerostin significantly increased over time, with a median relative change of 14.8% [IQR -7.9-41.4% (0.001 ng/ml/month), P < 0.001]. Serum DKK-1 did not significantly change over time. Serum BMP-7 increased over time in active disease (Ankylosing Spondylitis Disease Activity Score with CRP ≥1.3, P = 0.01), but the increase was less pronounced with TNF inhibitor (TNFi) use (P < 0.001). No determinant was associated with serum sclerostin change.

CONCLUSION

Serum BMP-7 change over 5 years was related with inflammation; it was increased in active disease, but the increase was low with TNFi use. Serum sclerostin levels significantly increased over time, but to a lesser degree than for serum BMP-7.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/, NCT01648907.

Gender-specific SBNO2 and VPS13B as a potential driver of osteoporosis development in male ankylosing spondylitis

To identify the critical genes and pathways that related to OP development in male AS patients, bioinformatic gene analysis and qRT-PCR validation were performed. SBNO2 and VPS13B were identified as the potential target for OP development, which may be valuable for the prevention of OP in male AS patients.

INTRODUCTION

Osteoporosis (OP) is common in men with ankylosing spondylitis (AS). The specific pathogenesis of OP in AS, however, is still unclear. The present study attempted to identify potential genes associated with the development of OP in males with AS.

METHODS

Gene expression profiles were downloaded from the GSE73754 and GSE35959 datasets from the Gene Expression Omnibus (GEO). Data from OsteoporosAtlas were downloaded as a supplement. Differentially expressed genes (DEGs) were determined with the limma package. The overlapping DEGs between male AS-related genes and OP-related genes were determined. The DEGs were validated by qRT-PCR in the blood samples of males with AS. Weighted gene co-expression network analysis (WGCNA) was utilized to establish a co-expression network to identify the hub genes.

RESULTS

A total of 17 overlapping DEGs were identified; 6 genes in 17 overlapping DEGs were verified as the essential genes in the pathogenesis of OP in male AS by qRT-PCR analysis. After WGCNA, the modules of MEblue (> 0.6) and MEred (> 0.8) were screened out by the correlation analysis and were determined to function mainly in MAPK signaling pathway and osteoclast differentiation. Analysis of the two modules revealed VPS13B and SBNO2 as key genes due to the high degree of correlation. Both genes play an important role in bone metabolism regulation in male AS. Two hub genes MYD88 in MEblue and NCK1 in MEred with high degree of connectivity were selected.

CONCLUSIONS

Gender-specific SBNO2 and VPS13B may be key genes involved in OP in male AS.

Exploring IL-17 in spondyloarthritis for development of novel treatments and biomarkers

Spondyloarthritis (SpA) is an umbrella term describing a family of chronic inflammatory rheumatic diseases. These diseases are characterised by inflammation of the axial skeleton, peripheral joints, and entheseal insertion sites throughout the body which can lead to structural joint damage including formation of axial syndesmophytes and peripheral osteophytes. Genetic evidence, preclinical and clinical studies indicate a clear role of interleukin (IL)- 23 and IL-17 as mediators in SpA pathogenesis. Targeting the IL-23/-17 pathways seems an efficient strategy for treatment of SpA patients, and despite the remaining challenges the pathway holds great promise for further advances and improved therapeutic opportunities. Much research is focusing on serological markers and imaging strategies to correctly diagnose patients in the early stages of SpA. Biomarkers may facilitate personalised medicine tailored to each patient's specific disease to optimise treatment efficacy and to monitor therapeutic response. This narrative review focuses on the IL-17 pathway in SpA-related diseases with emphasis on its role in pathogenesis, current approved IL-17 inhibitors, and the need for biomarkers reflecting core disease pathways for early diagnosis and measurement of disease activity, prognosis, and response to therapy.

Bone phenotypes in rheumatology - there is more to bone than just bone

Osteoarthritis, rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis, all have one clear common denominator; an altered turnover of bone. However, this may be more complex than a simple change in bone matrix and mineral turnover. While these diseases share a common tissue axis, their manifestations in the area of pathology are highly diverse, ranging from sclerosis to erosion of bone in different regions. The management of these diseases will benefit from a deeper understanding of the local versus systemic effects, the relation to the equilibrium of the bone balance (i.e., bone formation versus bone resorption), and the physiological and pathophysiological phenotypes of the cells involved (e.g., osteoblasts, osteoclasts, osteocytes and chondrocytes). For example, the process of endochondral bone formation in chondrocytes occurs exists during skeletal development and healthy conditions, but also in pathological conditions. This review focuses on the complex molecular and cellular taxonomy of bone in the context of rheumatological diseases that alter bone matrix composition and maintenance, giving rise to different bone turnover phenotypes, and how biomarkers (biochemical markers) can be applied to potentially describe specific bone phenotypic tissue profiles.

Aptamers for Proteins Associated with Rheumatic Diseases: Progress, Challenges, and Prospects of Diagnostic and Therapeutic Applications

Nucleic acid aptamers capable of affine and specific binding to their molecular targets have now established themselves as a very promising alternative to monoclonal antibodies for diagnostic and therapeutic applications. Although the main focus in aptamers’ research and development for biomedicine is made on cardiovascular, infectious, and malignant diseases, the use of aptamers as therapeutic or diagnostic tools in the context of rheumatic diseases is no less important. In this review, we consider the main features of aptamers that make them valuable molecular tools for rheumatologists, and summarize the studies on the selection and application of aptamers for protein biomarkers associated with rheumatic diseases. We discuss the progress in the development of aptamer-based diagnostic assays and targeted therapeutics for rheumatic disorders, future prospects in the field, and issues that have yet to be addressed.

Enhanced Osteogenic Differentiation of Human Bone Marrow Mesenchymal Stem Cells in Ossification of the Posterior Longitudinal Ligament Through Activation of the BMP2-Smad1/5/8 Pathway

Ossification of the posterior longitudinal ligament (OPLL) is characterized by ectopic OPLL. To date, the specific molecular pathogenesis of OPLL has not been clearly elucidated. In this study, bone marrow-derived mesenchymal stem cells obtained from healthy donors (HD-MSCs) and patients with OPLL (OPLL-MSCs) were cultured in osteogenic differentiation medium for 21 days. The osteogenic differentiation capacity was determined by alizarin red S (ARS) and alkaline phosphatase (ALP) assays. Gene expression levels of osteoblastic markers were measured by quantitative reverse transcription-polymerase chain reaction. Protein levels of related genes and the activation of related signaling pathways were measured by western blotting. LDN193189 was used to inhibit the Smad1/5/8 pathway, and small interfering RNA was used to regulate BMP2 expression. Our results showed that the OPLL-MSCs had stronger ARS staining and ALP activity and higher expression of RUNX2, Osterix, and OCN than the HD-MSCs. During osteogenic differentiation, the Smad1/5/8 pathway was overactivated in the OPLL-MSCs, and LDN193189 inhibition reversed the enhanced osteogenic ability of these cells. Besides, BMP2 was upregulated in the OPLL-MSCs. After BMP2 knockdown, the abnormal osteogenic differentiation of OPLL-MSCs was rescued. Thus, abnormal activation of the BMP2-Smad1/5/8 pathway induces enhanced osteogenic differentiation of OPLL-MSCs compared with HD-MSCs. These findings reveal a mechanism of pathological osteogenesis in OPLL and provide a new perspective on inhibiting pathological osteogenesis by regulating BMP2.

Applying precision medicine to unmet clinical needs in psoriatic disease

Psoriatic disease (PsD) is a heterogeneous condition that can affect peripheral and axial joints (arthritis), entheses, skin (psoriasis) and other structures. Over the past decade, considerable advances have been made both in our understanding of the pathogenesis of PsD and in the treatment of its diverse manifestations. However, several major areas of continued unmet need in the care of patients with PsD have been identified. One of these areas is the prediction of poor outcome, notably radiographic outcome in patients with psoriatic arthritis, so that stratified medicine approaches can be taken; another is predicting response to the numerous current and emerging therapies for PsD, so that precision medicine can be applied to rapidly improve clinical outcome and reduce the risk of toxicity. In order to address these needs, novel approaches, including imaging, tissue analysis and the application of proteogenomic technologies, are proposed as methodological solutions that will assist the dissection of the critical immune-metabolic pathways in this complex disease. Learning from advances made in other inflammatory diseases, it is time to address these unmet needs in a multi-centre partnership aimed at improving short-term and long-term outcomes for patients with PsD.

Bone turnover biomarkers, disease activity, and MRI changes of sacroiliac joints in patients with spondyloarthritis

The lack of valid biomarkers in patients with spondyloarthritis (SpA) requires searching for additional options to increase sacroiliac joint (SIJ) evaluation effectiveness. We assessed the serum levels of bone turnover markers and their relationships with active and chronic changes in SIJs using magnetic resonance imaging (MRI), indices, and laboratory parameters of disease activity in SpA patients. 102 patients with SpA and 15 healthy subjects were included. Testing of serum levels of transforming growth factor-beta (TGF-β1), Wnt3, sclerostin, and Dickkopf-1 (Dkk-1) was conducted. Active inflammatory lesions in SIJs were evaluated using Spondyloarthritis Research Consortium of Canada (SPARCC) MRI SIJ score, and chronic changes using the Danish scoring method. Bath Ankylosing Spondylitis Disease Activity Index, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), Ankylosing Spondylitis Disease Activity Scores with CRP, and ESR were used to assess disease activity. Serum levels of Dkk-1, TGF-β1, and sclerostin were significantly lower in SpA patients compared to healthy controls. The serum levels of Dkk-1 positively correlated with CRP. Dkk-1 had a significant negative correlation with Danish score. The sclerostin serum level had a weak negative correlation with the active inflammatory MRI SIJ lesions. There were positive correlations between TGF-β1 and sclerostin with Dkk-1, and negative correlation between Wnt3 and sclerostin. Dkk-1 positively correlated with CRP and negatively with chronic SIJ changes by Danish score. Sclerostin negatively correlated with the active SIJ lesions by SPARCC. This suggests that Dkk-1 and sclerostin are the most promising candidates to reveal inflammation and bone turnover in patients with SpA.

Biomarker development for axial spondyloarthritis

The term axial spondyloarthritis (axSpA) encompasses a heterogeneous group of diseases that have variable presentations, extra-articular manifestations and clinical outcomes, and that will respond differently to treatments. The prototypical type of axSpA, ankylosing spondylitis, is thought to be caused by interaction between the genetically primed host immune system and gut microbiota. Currently used biomarkers such as HLA-B27 status, C-reactive protein and erythrocyte sedimentation rate have, at best, moderate diagnostic and predictive value. Improved biomarkers are needed for axSpA to assist with early diagnosis and to better predict treatment responses and long-term outcomes. Advances in a range of 'omics' technologies and statistical approaches, including genomics approaches (such as polygenic risk scores), microbiome profiling and, potentially, transcriptomic, proteomic and metabolomic profiling, are making it possible for more informative biomarker sets to be developed for use in such clinical applications. Future developments in this field will probably involve combinations of biomarkers that require novel statistical approaches to analyse and to produce easy to interpret metrics for clinical application. Large publicly available datasets from well-characterized case-cohort studies that use extensive biological sampling, particularly focusing on early disease and responses to medications, are required to establish successful biomarker discovery and validation programmes.

An update on serum biomarkers to assess axial spondyloarthritis and to guide treatment decision

Axial spondyloarthritis (axSpA) is a group of debilitating, chronic, rheumatic conditions characterized by inflammation and new bone formation, mainly involving the spine and the sacroiliac joints. The lack of biomarkers in axSpA is well known. Despite significant treatment advances in recent years thanks to the introduction of drugs with a new mode of action, such as new biologic and targeted synthetic disease-modifying antirheumatic drugs, no relevant improvement in the identification of disease biomarkers has been achieved. Common parameters, such as erythrocyte sedimentation rate and C-reactive protein, which are routinely used to measure systemic inflammation, are the sole markers available to date and are not adequate to assess disease activity in all patients. The aim of this study is to review the most promising serum biomarkers that may help treatment decision in axSpA via a proper assessment of disease activity and identification of negative prognostic factors.

Added value of biomarkers compared with clinical parameters for the prediction of radiographic spinal progression in axial spondyloarthritis

OBJECTIVES

The objective of this study was to examine whether adding biomarkers to routine clinical parameters improves prediction of radiographic spinal progression in axial spondyloarthritis.

METHODS

One hundred and seventeen patients with ankylosing spondylitis who completed the Effects of NSAIDs on RAdiographic Damage in Ankylosing Spondylitis (ENRADAS) trial were included. Radiographic spinal progression was defined as worsening of the modified Stoke Ankylosing Spondylitis Spine Score by ⩾2 points after 2 years. A clinical prediction model was constructed out of baseline syndesmophytes, elevated CRP, cigarette smoking and male sex. The following serum biomarkers were measured at baseline by ELISA: MMP3, VEGF, calprotectin, leptin, high molecular weight adiponectin, osteoprotegerin, sclerostin, N-terminal telopeptide, procollagen type II N-terminal propeptide and serum amyloid A.

RESULTS

Repeated cross-validation analyses revealed one biomarker combination with potential added predictive value in addition to the clinical model: leptin + high molecular weight adiponectin + VEGF. This biomarker combination showed an area under the curve (AUC)Biomarkers = 0.731 (95% CI: 0.614, 0.848), which was numerically superior to the clinical model [AUCClinical = 0.665 (95% CI: 0.553, 0.776)]. A combination of clinical parameters + biomarkers showed an improved predictive value compared with the clinical model reflected by AUCClinical+Biomarkers = 0.768 (95% CI: 0.666, 0.871), though not statistically significant (P = 0.051). However, by considering the part of the receiver operating characteristic curve with a specificity ⩾75% resulting in partial AUC (pAUC), the improvement becomes significant (pAUCClinical+Biomarkers = 0.119; pAUCClinical = 0.053; P = 0.01).

CONCLUSION

Biomarkers show potential to improve the prediction of radiographic spinal progression in axial spondyloarthritis when used in addition to the clinical parameters, though the added value seems to be rather small.

Effects of 1-year anti-TNF-α therapies on bone mineral density and bone biomarkers in rheumatoid arthritis and ankylosing spondylitis

Objectives

Rheumatoid arthritis (RA) and ankylosing spondylitis (AS) have been associated with generalized and localized bone loss. We conducted a comprehensive study using imaging (dual-energy X-ray absorptiometry, DXA) and laboratory biomarkers in order to determine bone health and to study the effects of anti-tumor necrosis factor (TNF) biologics in RA and AS.

Patients and methods

Thirty-six RA and 17 AS patients undergoing 1-year etanercept (ETN) or certolizumab-pegol (CZP) therapy were studied. Bone density was assessed by DXA at baseline and after 12 months. Serum C-reactive protein (CRP), calcium, phosphate, parathyroid hormone (PTH), vitamin D3, osteocalcin, procollagen type I N-propeptide (P1NP), C-terminal telopeptide (βCTX), osteoprotegerin, sclerostin (SOST), Dickkopf-1 (DKK-1), soluble receptor activator nuclear kappa B ligand (sRANKL), and cathepsin K (cathK) levels were determined at baseline and after 6 and 12 months.

Results

TNF-α inhibition was clinically effective. Anti-TNF-α halted further bone loss over 1 year. In general, anti-TNF therapy significantly increased P1NP, SOST levels, and the P1NP/βCTX ratios, while decreased DKK-1 and CathK production at different time points in most patient subsets. In the full cohort and in RA, baseline and/or 12-month bone mineral density (BMD) at multiple sites exerted inverse relationships with CRP and βCTX, and positive correlation with SOST. In AS, L2-4 BMD after 1-year biologic therapy inversely correlated with baseline βCTX, while femoral neck BMD rather showed inverse correlations with CRP.

Conclusions

Anti-TNF therapy slowed down generalized bone loss, in association with clinical improvements, in both diseases. TNF blockade may enhance bone formation and suppress joint destruction. Anti-TNF therapy may act inversely on DKK-1 and SOST. Independent predictors of BMD were SOST and βCTX in RA, whilst CRP in AS.Key Points• One-year anti-TNF therapy halted generalized bone loss in association with clinical improvement in arthritides.• Anti-TNF therapy may inversely act on DKK-1 and SOST.• Independent predictors of BMD were SOST and βCTX in RA, while CRP in AS.

Biomarkers in Inflammatory Bowel Disease-Associated Spondyloarthritis: State of the Art and Unmet Needs

Inflammatory bowel disease-associated spondyloarthritis is a systemic disease characterized by the chronic inflammation of both the gastrointestinal tract and the musculoskeletal system. Since inflammatory bowel disease-associated spondyloarthritis has been associated with a significant diagnostic delay, which may lead to poor quality of life and progression of joint damage, efforts to discover new reliable and noninvasive diagnostic biomarkers have been made. We reviewed the state of the art of biomarker research in inflammatory bowel disease-associated spondyloarthritis, showing that to date it has been largely unsatisfactory. Only a few of the biomarkers that have been investigated are likely to enter the clinical practice upon further validation in independent cohorts. The research of new and innovative biomarkers for inflammatory bowel disease-associated spondyloarthritis is warranted.

Serum Sclerostin and Bone Morphogenetic Protein-2 Levels in Patients with Ankylosing Spondylitis: A Meta-Analysis

Various studies have investigated the serum sclerostin and bone morphogenetic protein-2 (BMP-2) levels in patients with ankylosing spondylitis (AS), but the results were inconsistent. The aim of this meta-analysis was to synthetically assess the associations of serum levels of sclerostin and BMP-2 with AS. Multiple electronic databases were searched to locate relevant articles published before November 2018. Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated by the random-effect model. Totally, 21 studies were included. Meta-analysis results showed no significant difference between AS group and control group in serum sclerostin levels (SMD = 0.098, 95% CI - 0.395 to 0.591, p = 0.697). Nevertheless, serum BMP-2 levels in AS patients were higher than that in controls (SMD = 1.184, 95% CI 0.209 to 2.159, p = 0.017). Subgroup analysis demonstrated that European and South American AS patients had lower serum levels of sclerostin than controls. AS patients with age ≥ 40 years, erythrocyte sedimentation rate (ESR) ≤ 20 mm/h and Bath Ankylosing Spondylitis Functional Index (BASFI) < 4 had statistically significant lower serum sclerostin concentrations compared to controls. Chinese and Korean AS patients as well as patients with lower CRP had higher serum BMP-2 levels than controls, and country may be a source of heterogeneity across the studies. No publication bias existed and sensitivity analysis confirmed the stability of results. Serum BMP-2, but not sclerostin levels may be closely related to the development of AS.

Association of Genetic Variants of RANK, RANKL, and OPG with Ankylosing Spondylitis Clinical Features in Taiwanese

Ankylosing spondylitis (AS) is a chronic inflammatory disease that leads to spinal ankylosis. The receptor activator of the nuclear factor-kappa (RANK), RANK ligand, and osteoprotegerin (OPG) (RANK/RANKL/OPG) pathway plays critical roles in bone metabolism and the immune system. The current study was aimed at investigating whether six single-nucleotide polymorphisms (SNPs) within the RANK, RANKL, and OPG genes essential for bone homeostasis are associated with AS. Genotype distributions, allele and haplotype frequencies, were compared between 1120 AS patients and 1435 healthy controls and among AS patients with stratification by syndesmophyte formation, onset age, and HLA-B27 positivity. We found that RANKL SNPs were associated with AS syndesmophyte formation. Notably, the RANKL SNP haplotype rs7984870C/rs9533155G/rs9525641C was negatively associated with AS susceptibility and appeared to protect against syndesmophyte formation in AS. Functionally, RANKL promoter SNPs (rs9525641 C/T and rs9533155 G/C) affected DNA-protein complex formation and promoter activity in promoter reporter analyses. The OPG SNP haplotype rs2073618G/rs3102735T was significantly associated with HLA-B27 negativity in AS patients. Furthermore, AS patients with syndesmophyte formation had significantly lower levels of soluble RANKL levels than those without syndesmophyte formation. Our data suggested a role for RANKL in AS susceptibility and severity.

Unmet Needs in Axial Spondyloarthritis

During the past decade, the well-known disease called ankylosing spondylitis has come to be considered as a subset of the broader entity referred as axial spondyloarthritis (axSpA), which also includes non-radiographic axSpA. The need of this new classification was aimed to improve the sensitivity for an early diagnosis, to reduce diagnostic delay, and to allow an early treatment. Although there is improvement in the recognition, the management of patients, and the treatment strategies of axSpA, unmet needs persist. There is still a substantial gap of 5-8 years between the onset of symptoms and the diagnosis of axSpA and, even in patients diagnosed early, 20-40% of them do not respond or have a loss of response to anti-TNF treatment. Moreover, the pathogenesis of the disease and, in particular, the mechanisms of new bone formation are far to be completely understood. Nevertheless, the discovery of IL-23/IL-17 axis with the development of biologic inhibitors, the identification of new subsets of effector cells, together with the interest in the detection of potential biomarkers of bone formation brought the approach to axSpA into a new era. This review is intended to enhance awareness and understanding of axSpA and to identify and discuss the current unmet needs in axSpA, including diagnosis, classification, biomarkers, pathogenesis, management, and treatment strategies.

Association of Serum Sclerostin with Bone Sclerostin in Chronic Kidney Disease is Lost in Glucocorticoid Treated Patients

The osteocytic protein sclerostin inhibits bone turnover. Serum sclerostin rises early in chronic kidney disease (CKD), but if this reflects osteocyte sclerostin production is unclear, since sclerostin is also expressed in extra-skeletal tissue. Glucocorticoid treatment impacts on serum sclerostin, but the effect on the association between serum and bone sclerostin is unknown. We sought to determine whether serum sclerostin reflects bone sclerostin in different CKD stages and how this association is influenced by glucocorticoid treatment. In a cross-sectional analysis, we investigated serum sclerostin, bone sclerostin by immunohistochemistry, and bone histomorphometry in iliac crest bone biopsies from 43 patients with CKD 3-5D, including 14 dialysis patients and 22 transplanted patients (18 kidney, 4 other). Thirty-one patients were on glucocorticoid treatment at time of biopsy. Patients with low bone turnover (bone formation rate < 97 µm²/mm²/day; N = 13) had higher median serum sclerostin levels (224.7 vs. 141.7 pg/ml; P = 0.004) and higher bone sclerostin, expressed as sclerostin positive osteocytes per bone area (12.1 vs. 5.0 Scl+ osteocytes/B.Ar; P = 0.008), than patients with non-low bone turnover (N = 28). In linear regression analyses, correcting for age, gender, dialysis status and PTH, serum sclerostin was only associated with bone sclerostin in patients not treated with glucocorticoids (r² = 0.6, P = 0.018). For the first time, we describe that female CKD patients have higher median bone sclerostin than males (11.7 vs. 5.7 Scl+ osteocytes/B.Ar, P = 0.046), despite similar serum sclerostin levels and bone histo-morphometric parameters. We conclude that glucocorticoid treatment appears to disrupt the association of serum sclerostin with bone sclerostin in CKD.

lncRNA MEG3 is downregulated in ankylosing spondylitis and associated with disease activity, hospitalization time and disease duration

Long non-coding (lnc)RNA maternally expressed gene 3 (MEG3) has been proved to participate in osteoporosis, which features inverse pathological changes to those associated with spondylosis. The present study aimed to investigate the involvement of lncRNA MEG3 in ankylosing spondylitis. Blood and open sacroiliac joint biopsies were obtained from ankylosing spondylitis patients and healthy controls, and the expression of MEG3 in those tissues was detected by reverse-transcription-quantitative polymerase chain reaction analysis. Disease activity was evaluated according to the Ankylosing Spondylitis Disease Activity Score established by the International Association of Ankylosing Spondylitis. The diagnostic value of MEG3 expression for ankylosing spondylitis was evaluated by receiver operating characteristic curve analysis. The correlation between MEG3 expression and disease activity was assessed using Pearson correlation analysis. Furthermore, according to the median expression level of MEG3, patients were divided into high-level and low-level groups. The hospitalization time and re-hospitalization rate within 2 years after discharge were compared between these two groups and differences in clinicopathological parameters between the two groups were analyzed using the chi-square test. The results indicated that MEG3 was downregulated in ankylosing spondylitis patients compared with that in healthy controls. Furthermore, MEG3 expression levels may be used to effectively distinguish ankylosing spondylitis patients from healthy controls. The serum levels of MEG3 were not associated with the patients' age, sex or alcohol/tobacco consumption, but closely correlated with disease activity and disease duration. In addition, patients with higher expression levels of MEG3 had a shorter hospitalization time and a lower re-hospitalization rate within 2 years after discharge It was concluded that lncRNA MEG3 is downregulated in ankylosing spondylitis patients and is associated with disease activity, time of hospitalization and disease duration.

Monocytes from male patients with ankylosing spondylitis display decreased osteoclastogenesis and decreased RANKL/OPG ratio

The present study investigates the osteoclastogenic capacity of peripheral blood mononuclear cells (PBMCs) in male patients with ankylosing spondylitis (AS). We demonstrated that monocytes from these patients display a lower capacity to generate osteoclasts compared to cells from healthy controls, and osteoclastogenesis was negatively correlated with disease duration.

INTRODUCTION

Ankylosing spondylitis (AS) is a disease characterized by new bone growth that leads to syndesmophyte formation but AS patients frequently present with low bone mineral density/fractures. Osteoclastogenesis in AS patients is poorly studied and controversial. The aim of this study is to determine if the osteoclastogenic capacity of PBMCs is different in AS patients compared to controls and the relationship between osteoclastogenesis and clinical/laboratory parameters.

METHODS

PBMCs from 85 male AS patients and 59 controls were tested for CD16+ cells and induced to differentiate into osteoclasts over 3 weeks in vitro. Serum levels of RANKL, osteoprotegerin (OPG), C-terminal telopeptide of type I collagen (CTX), and amino-terminal pro-peptide of type I collagen (P1NP) were also evaluated.

RESULTS

PBMCs from AS patients had fewer CD16+ cells and produced fewer osteoclasts compared to controls. Apoptosis occurred less frequently in osteoclasts obtained from AS patients than in osteoclasts from the controls. A lower RANKL/OPG and CTX/P1NP were observed in AS patients compared to controls. AS patients taking NSAIDs presented no difference regarding the number of OCs produced and the percentage of CD16+ cells compared to controls. However, patients taking TNF inhibitors (TNFi) presented lower OC numbers than controls. A negative correlation was demonstrated between the number of osteoclasts generated from PBMCs of AS patients and disease duration.

CONCLUSION

Monocytes from male AS patients display a lower capacity to generate osteoclasts in vitro compared to cells from controls. Osteoclastogenesis was negatively correlated with disease duration. This finding supports the idea that osteoclasts play a role in the physiopathology of bone disease in AS patients.

Low bone mineral density predicts the formation of new syndesmophytes in patients with axial spondyloarthritis

Background

This study aimed to investigate whether the presence of low bone mineral density (BMD) in patients with axial spondyloarthritis (axSpA) predicts formation of new syndesmophytes over 2 years.

Methods

One hundred and nineteen patients fulfilling the imaging arm of the Assessment of SpondyloArthritis International Society axSpA criteria were enrolled. All patients were under 50 years of age. The modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) was assessed by two trained readers blinded to the patients’ data. BMD (lumbar spine, femoral neck or total hip) at baseline was assessed using dual-energy absorptiometry. Low BMD was defined as Z score ≤ − 2.0. Spinal radiographic progression was defined as worsening of the mSASSS by ≥ 2 points over 2 years. Logistic regression analyses were performed to identify predictors associated with development of new syndesmophytes and spinal radiographic progression.

Results

At baseline, 19 (16%) patients had low BMD. New syndesmophytes had developed in 22 (21%) patients at 2-year follow-up. New syndesmophyte formation after 2 years occurred more in patients with low BMD than in those with normal BMD (p = 0.047). In the multivariable analysis, current smoking, existing syndesmophytes and low BMD at baseline were associated with spinal radiographic progression (OR (95% CI) 3.0 (1.1, 7.7), 4.6 (1.8, 11.8) and 3.6 (1.2, 11.2), respectively). The presence of syndesmophytes at baseline and low BMD were predictors of new syndesmophytes over the following 2 years (OR (95% CI) 5.5 (2.0, 15.2) and 3.6 (1.1, 11.8), respectively).

Conclusions

Low BMD and existing syndesmophytes at baseline were independently associated with the development of new syndesmophytes in young axSpA patients.

The role of smoking in the development and progression of structural damage in axial SpA patients: A systematic review and meta-analysis

OBJECTIVE

The objective of this study was to determine whether smoking was associated with the cumulative radiographic spinal damage and radiographic progression in patients with ankylosing spondylitis (AS). Thus, we conducted a systematic review and meta-analysis of the available studies to date.

METHODS

An electronic search was conducted from inception to June 21, 2016, in EMBASE, the MEDLINE/PubMed Cochrane Central Register of Controlled Trials databases. Cross-sectional and longitudinal cohort studies investigating the association between smoking and cumulative spinal structural damage or radiographic progression were included. The outcome of interest was the presence of syndesmophytes in cross-sectional studies and radiographic progression in longitudinal studies. The quality assessment was done using the Agency for Healthcare Research and Quality checklist. The authors of potentially relevant studies were contacted regarding the unpublished data. Data from eligible cross-sectional studies were extracted and arranged in a 2x2 table. The odds ratios (ORs) and 95% confidence intervals (CIs) for the dichotomous outcome of interest were computed.

RESULTS

The combined data of eight eligible cross-sectional studies for the assessment of association between smoking and cumulative spinal structural damage suggested a significant association (OR, 2.02; 95% CI, 1.51-2.70). No significant heterogeneity was detected between studies (I²=23.0%, p=0.25). The heterogeneity of the longitudinal study data did not permit us to undertake a meta-analysis. Hence, a qualitative review was performed.

CONCLUSION

The results of our meta-analysis show that smoking is associated with increased cumulative spinal structural damage in patients with AS. Therefore, rheumatologists should encourage patients with AS to quit smoking.

Spine Fractures in Ankylosing Diseases: Recommendations of the Spine Section of the German Society for Orthopaedics and Trauma (DGOU)

STUDY DESIGN

Review of literature and case series.

OBJECTIVES

Update and review of current treatment concepts for spine fractures in patients with ankylosing spinal disorders.

METHODS

Case presentation and description of a diagnostic and therapeutic algorithm for unstable spinal injuries with an underlying ankylosing spinal disorder (ASD) of the cervical and thoracolumbar spine.

RESULTS

Nondisplaced fractures can be missed easily using conventional X-rays. Thus, computed tomography (CT) scans are recommended for all trauma patients with ASD. In doubt or presence of any neurologic involvement additional magnetic resonance imaging (MRI) scans should be obtained. Spine precautions should be maintained all times and until definitive treatment (<24 h). Nonoperative fracture treatment is not recommended given the mechanical instability of the most commonly seen fracture patterns (AOSpine B- and C-type, M2) in patients with ASD and inherent high risk of secondary neurologic deterioration. For patients with ankylosing spondylitis (AS) or diffuse idiopathic hyperostosis (DISH) sustaining cervical spine fractures, a combined anterior-posterior instrumentation for fracture fixation is recommended. Closed reduction and patient positioning can be challenging in presence of preexisting kyphotic deformities. In the thoracolumbar (TL) spine, a posterior instrumentation extending 2 to 3 levels above and below the fracture level is recommended to maintain adequate reduction and stability until fracture healing. Minimally invasive percutaneous pedicle screws and cement augmentation can help to minimize the surgical trauma and strengthen the construct stability in patients with diminished minor bone quality (osteopenia, osteoporosis).

CONCLUSIONS

Current concepts, treatment options, and recommendations of the German Orthopedic Trauma Society-Spine Section for spinal fractures in the ankylosed spine have been outlined.

Changes in bone mineral density and bone metabolic indexes in ankylosing spondylitis mouse model complicated with osteoporosis

Changes in bone mineral density and bone metabolic indexes in a model of ankylosing spondylitis (AS) mice complicated with osteoporosis (OP) were investigated. BLAB/c mice were used as the subjects. AS was induced using proteoglycan, and OP was induced using tail suspension method. The mice were randomly divided into four groups: AS group, OP group, AS + OP group and negative control group. Changes in bone mineral density, bone strength, serum calcium (Ca), phosphorus, alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRACP), in mice of each group were detected and compared. There were statistically significant differences in bone mineral density and bone strength among groups. Compared with the negative control group, bone mineral density and bone strength in the AS, the OP and the AS + OP groups were significantly decreased, and the lowest bone mineral density and bone strength were found in the AS + OP group (P<0.05). There were no significant differences in bone mineral density and bone strength between the AS group and the OP group. Significant differences in serum Ca, ALP and TRACP but not in serum phosphorus were found among groups. Compared with the control group, serum levels of Ca and TRACP in the AS, the OP and the AS + OP groups were significantly increased, while levels of ALP were obviously decreased (P<0.05). Bone destruction in AS mice complicated with osteoarthritis was more serious than that in mice with simple AS.

Serum bone-turnover biomarkers are associated with the occurrence of peripheral and axial arthritis in psoriatic disease: a prospective cross-sectional comparative study

Background

A recent systematic review identified four candidate serum-soluble bone-turnover biomarkers (dickkopf-1, Dkk-1; macrophage-colony stimulating factor, M-CSF; matrix metalloproteinase-3, MMP-3; osteoprotegerin, OPG) showing possible association with psoriatic arthritis (PsA). We aimed to: (i) confirm and determine if these four biomarkers are associated with PsA; (ii) differentiate psoriasis cases with and without arthritis; and (iii) differentiate PsA cases with and without axial arthritis.

Methods

A prospective cross-sectional comparative two-centre study recruited 200 patients with psoriasis without arthritis (PsC), 127 with PsA without axial arthritis (pPsA), 117 with PsA with axial arthritis (psoriatic spondyloarthritis, PsSpA), 157 with ankylosing spondylitis (AS) without psoriasis, and 50 matched healthy controls (HC). Serum biomarker concentrations were measured using ELISA. Multivariable regression and receiver operating characteristic analyses were performed.

Results

MMP-3 concentrations were significantly higher and M-CSF significantly lower in each arthritis disease group compared with HC (p ≤ 0.02). MMP-3 concentrations were significantly higher (adjusted odds ratio, OR_adj 1.02 per ng/ml increase in concentration; p = 0.0004) and M-CSF significantly lower (OR_adj 0.44 per ng/ml increase; p = 0.01) in PsA (pPsA and PsSpA combined) compared with PsC. Dkk-1 concentrations were significantly higher (OR_adj 1.22 per ng/mL increase; p = 0.01), and OPG concentrations significantly lower (OR_adj 0.20 per ng/mL increase; p = 0.02) in patients with axial arthritis (PsSpA and AS combined) than in those without (pPsA). Furthermore, Dkk-1 concentrations were significantly higher along a spectrum of increasing axial arthritis; Dkk-1 concentrations were higher in AS compared with PsSpA (OR_adj 1.18 per ng/mL increase; p = 0.02). Receiver operating characteristic analysis showed MMP-3 to be the best single biomarker for differentiating PsA from PsC (AUC 0.70 for a cut-off of 14.51 ng/mL; sensitivity 0.76, specificity 0.60).

Conclusions

MMP-3 and M-CSF are biomarkers for the presence of arthritis in psoriatic disease, and could therefore be used to screen for PsA in psoriasis cohorts. Dkk-1 and OPG are biomarkers of axial arthritis; they could therefore be used to screen for the presence of axial disease in PsA cases, and help differentiate PsSpA from AS. High concentrations of Dkk-1 in AS and PsSpA compared with HC, support previous reports that Dkk-1 is dysfunctional in the spondyloarthritides.

Evaluation of periostin and factors associated with new bone formation in ankylosing spondylitis: Periostin may be associated with the Wnt pathway

OBJECTIVE

Periostin has been shown to be involved in bone anabolism through the regulation of Wnt-β-catenin signaling. It may be one of the pathogenic mechanisms in syndesmophyte formation in ankylosing spondylitis (AS). The aim of this study was to evaluate serum periostin levels in patients with AS and to assess relationships among biomarkers of bone formation and periostin in disease outcomes, particularly radiographic changes.

METHODS

Ninety-seven consecutive AS patients (78% male) and 48 healthy controls (75% male) were included in the study. Serum periostin, dickkopf-1 (DKK-1), sclerostin and vascular endothelial growth factor (VEGF) levels were measured using commercially available enzyme-linked immunosorbent assay kits. Disease-related characteristics of patients were assessed using Ankylosing spondylitis disease activity score - C-reactive protein (ASDAS-CRP), Bath AS Disease Activity Index, Bath AS Functional Index and Bath AS metrology index. Radiographs were scored using the modified New York criteria and modified Stokes AS spinal score (mSASSS).

RESULTS

Compared with control subjects, patients with AS had significantly lower serum levels of periostin (P < 0.001) and sclerostin (P < 0.001), but higher serum levels of VEGF (P < 0.001) and high-sensitivity CRP (P < 0.001). Serum periostin (P = 0.005) and sclerostin levels (P = 0.016) were significantly lower in patients with very high disease activity according to ASDAS-CRP. Current age (P = 0.009), age at symptom onset (P = 0.021) and hip joint involvement (P = 0.012) were independently associated with the development of syndesmophyte, in contrast to biomarkers of bone metabolism that we evaluated.

CONCLUSION

Our results suggest that periostin is down-regulated in AS patients with highly active disease and may contribute to disease pathogenesis through an interaction with Wnt signaling.

Serum Sclerostin Levels in Patients with Ankylosing Spondylitis and Rheumatoid Arthritis: A Systematic Review and Meta-Analysis

Objective. Current studies of serum sclerostin levels in AS and RA patients are inconsistent. This meta-analysis was performed to identify the association of serum sclerostin level with AS and RA patients. Methods. Embase, PubMed, MEDLINE, and Cochrane Library databases (up to 25 January 2017) were used to collect all relevant published articles. Studies were pooled and standard mean difference (SMD) with 95% confidence interval (CI) was calculated. All data analyses were performed using RevMan 5.3. Results. Totally eight studies of AS including 420 AS patients and 317 healthy controls (HC) and three studies of RA including 145 RA patients and 127 HC were finally included in this meta-analysis. The results revealed that the serum sclerostin levels in both AS patients (SMD = −0.14; 95% CI = [−0.39,0.11]; P = 0.28) and RA patients (SMD = −0.10; 95% CI = [−0.34,0.15]; P = 0.43) were not significantly different from those in HC. Conclusion. The difference of serum sclerostin levels in AS and RA patients was not significantly different from HC, indicating that the sclerostin may not associate with the development of AS and RA.

Bone as a Target Organ in Rheumatic Disease: Impact on Osteoclasts and Osteoblasts

Dysregulated bone remodeling occurs when there is an imbalance between bone resorption and bone formation. In rheumatic diseases, including rheumatoid arthritis (RA) and seronegative spondyloarthritis, systemic and local factors disrupt the process of physiologic bone remodeling. Depending upon the local microenvironment, cell types, and local mechanical forces, inflammation results in very different effects on bone, promoting bone loss in the joints and in periarticular and systemic bone in RA and driving bone formation at enthesial and periosteal sites in diseases such as ankylosing spondylitis (AS), included within the classification of axial spondyloarthritis. There has been a great deal of interest in the role of osteoclasts in these processes and much has been learned over the past decade about osteoclast differentiation and function. It is now appreciated that osteoblast-mediated bone formation is also inhibited in the RA joint, limiting the repair of erosions. In contrast, osteoblasts function to produce new bone in AS. The Wnt and BMP signaling pathways have emerged as critical in the regulation of osteoblast function and the outcome for bone in rheumatic diseases, and these pathways have been implicated in both bone loss in RA and bone formation in AS. These pathways provide potential novel approaches for therapeutic intervention in diseases in which inflammation impacts bone.

Ankylosing Spondylitis Patients Have Impaired Osteoclast Gene Expression in Circulating Osteoclast Precursors

INTRODUCTION

Ankylosing spondylitis (AS) is typically characterized by focal bone overgrowth and also by systemic bone loss. We hypothesize that the increased osteoproliferation found in AS might be partially due to reduced ability of osteoclast precursors (OCPs) to differentiate into osteoclasts (OCs). Therefore, our aim was to characterize bone remodeling and pro-osteoclastogenesis inflammatory environment, monocytes' phenotype, and in vitro osteoclast differentiation in AS patients.

METHODS

Patients with active AS without any ongoing therapy and age- and gender-matched healthy donors were recruited. Receptor activator of nuclear factor-κβ (RANKL) surface expression on circulating leukocytes and frequency and phenotype of monocyte subpopulations were assessed. Quantification of serum levels of bone turnover markers and cytokines, in vitro OC differentiation assay and quantitative reverse transcription real-time PCR for OC-specific genes were performed.

RESULTS

Pro- and anti-inflammatory cytokine serum levels were higher in AS patients than in controls. RANKL neutrophil expression was higher in AS patients when compared to healthy donors, but CD51/CD61 expression was lower in the classical monocyte subpopulation. Concerning osteoclastogenesis, we found no differences in the in vitro osteoclast differentiating potential of these cells when compared to healthy donors. However, we observed low expression of CSF1R, RANK, and NFATc1 in AS OCPs.

CONCLUSION

Despite the high levels of pro-inflammatory cytokines present in AS patients, no differences in the number of OC or resorbed area were found between AS patients and healthy donors. Moreover, we observed that OCPs have low OC-specific gene expression. These findings support our hypothesis of an impaired response of OCPs to pro-osteoclastogenic stimuli in vivo in AS patients.

Increasing smoking intensity is associated with increased disease activity in axial spondyloarthritis

A history of ever-smoking appears to be associated with a more severe disease phenotype in axial spondyloarthritis (axSpA). However, evidence is sparse for the effect of increased smoking exposure on disease outcomes or whether smoking reduction or cessation improves outcomes. The aim of this study was to explore whether a dose–response relationship exists between pack-years and disease activity and functional impairment in axSpA. Consecutive patients meeting ASAS criteria for axial SpA were recruited from a spondyloarthritis service. The associations between pack-years of smoking and: (1) disease activity (BASDAI/ASDAS), (2) spinal pain, (3) functional impairment (BASFI) and (4) inflammatory markers were explored using multivariable linear models, adjusted for age, gender and use of TNF inhibition (TNFi) therapy. Pack-years were categorised into four groups (<10, 11–20, 21–40, >40) and analysed with light smoking (<10) as reference. Two hundred and thirty-eight axSpA patients were recruited: 76% were male, mean age 46.4 years (SD ± 13.7), and 33% were treated with TNFi. One hundred and twelve patients reported history of ever-smoking with median pack-year 20 [IQR10-30]. Compared to light smokers, those with higher categories of smoking exposures had higher BASDAI (21–40 pack-years, β = 1.6 (95% CI 0.28, 2.95); >40, β = 2.6 (0.54, 3.56)), higher BASFI (21–40, β = 2.1 (0.42, 4.80); >40, β = 3.2 (0.76, 5.71)), and higher ASDAS (21–40, β = 0.82 (0.14, 1.51)). This cross-sectional study demonstrated that smoking is associated with increased axSpA severity markers in a dose–response manner. Particular effort should be made to restrict smoking exposure early before accruing a significant number of pack-years.

Serum levels of Dkk-1, sclerostin and VEGF in patients with ankylosing spondylitis and their association with smoking, and clinical, inflammatory and radiographic parameters

OBJECTIVE

To evaluate serum Dickkopf-1 (Dkk-1), sclerostin and vascular endothelial growth factor (VEGF) levels in patients with ankylosing spondylitis (AS) compared to healthy controls as well as their association with smoking, and clinical, inflammatory and radiographic parameters.

METHODS

Serum samples for total Dkk-1, sclerostin and VEGF were obtained from 57 tumour necrosis factor (TNF) inhibitor naïve patients with AS and 34 sex-, age- and body mass index (BMI)-matched controls. The erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Bath AS Disease Activity Index (BASDAI), Bath AS Functional Index (BASFI), modified Stroke AS Spine Score (mSASSS) and smoking status were assessed for each patient.

RESULTS

There was no significant difference in serum bone metabolism markers between AS patients and controls. Dkk-1 levels were significantly (P<0.05) higher in AS patients with elevated ESR and CRP and no syndesmophytes, and were significantly (P<0.001) correlated with sclerostin levels (r=0.592). VEGF levels were significantly (P<0.05) higher in AS patients with current and ever smoking, elevated ESR and CRP, and high BASDAI and BASFI, and were significantly (P<0.05) correlated with ESR (r=0.284), CRP (r=0.285), BASDAI (r=0.349) and BASFI (r=0.275). In multivariate regression analyses, high Dkk-1 levels were significantly (P≤0.001) associated with elevated ESR and CRP, no syndesmophytes and high sclerostin levels, and high VEGF levels significantly (P<0.05) with ever smoking, and elevated ESR and CRP.

CONCLUSION

In AS, serum Dkk-1 concentrations appear to be related not only to syndesmophyte formation but also to systemic inflammation. Furthermore, high VEGF levels may be associated with smoking exposure.