High disease activity in ankylosing spondylitis is associated with increased serum sclerostin level and decreased wingless protein-3a signaling but is not linked with greater structural damage

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.

Serum DKK-1 level in ankylosing spondylitis: insights from meta-analysis and Mendelian randomization

Objective

The purpose of this study was to precisely evaluate the serum Dickkopf-1 (DKK-1) level in patients with ankylosing spondylitis (AS) relative to that in normal controls and to test the causal relationship between DKK-1 and the risk of AS.

Methods

Embase, PubMed, Web of Science, WANFANG DATA, VIP, and China National Knowledge Infrastructure (CNKI) were comprehensively searched until July 2022 for pertinent studies. The pooled standardized mean difference (SMD) with a 95% confidence interval (CI) was calculated by the fixed or random-effect model. In Mendelian randomization (MR) analysis on the causal relationship between serum DKK-1 level and AS risk, the inverse variance weighting method (IVW), MR-Egger regression, weighted median method, and weighted pattern method were applied. Sensitivity analyses, including the horizontal pleiotropy test, heterogeneity test, and leave-one-out test, were also performed.

Results

The meta-analysis of 40 studies containing 2,371 AS patients and 1,633 healthy controls showed that there was no significant difference in DKK-1 serum level between AS patients and normal controls (pooled SMD=0.207, 95% CI =-0.418-0.832, P=0.516). The subgroup analysis of the CRP ≤ 10 mg/L group showed that AS patients had higher serum DKK-1 concentration than the healthy controls (SMD=2.267, 95% CI = 0.102-4.432, P=0.040). Similarly, MR analysis also demonstrated no significant association between DKK-1 serum level and AS (IVW OR=0.999, 95% CI = 0.989-1.008, P=0.800). All sensitivity analyses revealed consistent results.

Conclusions

There was no significant change in serum DKK-1 concentration between AS patients and healthy controls. In addition, no causal relationship exists between serum DKK-1 levels and AS risk.

The Increasing Level of DKK-1 as a New Bone Formation Factor in Patients with Early Spondyloarthritis

The role of dickkopf-related protein 1 (DKK-1) in radiographic development may become a robust marker for early spondyloarthritis (SpA) diagnosis. This study aimed at determining the serum DKK-1 profile in patients with SpA and investigating its relationship with SpA progression. Supported by analyzing the BMD data which aims to affirm the potential of DKK-1 as a biomarker for early diagnosis of SpA, this research may become the early study to produce a robust tool to diminish the fatal impacts in SpA. This cross-sectional study included patients with SpA using ASAS 2010 criteria from Dr. Soetomo General Hospital, Indonesia. Collected data included patients' general characteristics, disease duration, disease activity using ASDAS-CRP and ASDAS-ESR, serum DKK-1 levels, and BMD. The patients were classified as early SpA if the disease duration was ≤5 years and established SpA if the disease duration was >5 years, while the low BMD was indicated by Z score ≤ -2.00. The correlation was tested using the Spearman or Pearson test. The differences in patients' characteristics among early and established SpA and also between low and normal BMD were tested using the unpaired T-test or the Mann-Whitney test. The serum DKK-1 levels in early SpA (7365 ± 2067 pg/dL) were significantly higher than those in established SpA (5360 ± 1054 pg/dL). Serum DKK-1 levels were also associated with disease duration (r = -0.370, p = 0.040) and BMD at the total hip (r = 0.467, p = 0.028). The differences in all patients' clinical parameters were not found between patients with low BMD at any site and patients with normal BMD unless in the BMI (p = 0.019). Our findings found DKK-1 as a potential diagnostic marker for early SpA. Early diagnosis may lead to rapid treatment to delay disease progression and prevent future impairment.

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.

The TNF-NF-kB-DKK1 Axis Promoted Bone Formation in the Enthesis of Ankylosing Spondylitis

Objective

This study aimed to determine the serum Dickkopf 1 (DKK1) levels in ankylosing spondylitis (AS) patients and decipher the mechanism of tumor necrosis factor (TNF)-mediated DKK1 regulation in human AS enthesis cells.

Methods

The sera were obtained from 103 patients with AS and 30 healthy controls (HCs) The enthesis of facet joints were obtained from 4 AS patients and 5 controls The serum levels of DKK1 were measured using ELISA and compared between AS and HCs The impact of TNF on DKK1 expression in human primary spinal enthesis cells was evaluated using various molecular biology techniques and bone formation indicators.

Results

AS patients showed higher serum DKK1 levels than HCs after adjusting for age (9174 [6153∼1,3100] pg/mL vs 8262 [6703∼9278] pg/mL, p=0043) TNF treatment promoted bone formation and DKK1 expression in both control enthesis cells and those of AS This enhanced bone formation by TNF was pronounced in AS-enthesis than those of controls Mechanically, TNF induced NF-kB activation upregulates the DKK1 transcript level While, NF-kB inhibitor led to downregulate DKK1 expression in the enthesis Besides, DKK1 overexpression promoted bone formation in enthesis.

Conclusion

TNF induced DKK1 expression in the enthesis through NF-kB activation TNF-induced DKK1 expression may play a bone formation in the radiologic progression of ankylosing spondylitis.

Measuring Serum Sclerostin in Egyptian Patients With Systemic Lupus Erythematosus and Evaluating Its Effect on Disease Activity: A Case-Control Study

OBJECTIVE

Sclerostin is an osteocyte-secreted protein that downregulates bone formation by blocking the Wnt/β-catenin signaling pathway. Sclerostin can be induced by inflammation, and high levels have been reported in patients with proteinuria and renal impairment. Studies evaluating the role of sclerostin in systemic lupus erythematosus (SLE) patients are scarce. This study aims to measure serum sclerostin in SLE patients and correlate its level with bone biomarkers and disease activity, particularly in lupus nephritis and arthritis. Finally, we evaluated factors that may predict sclerostin concentrations.

METHODS

This cross-sectional, case-control study was conducted from May 2017 to April 2018. Serum sclerostin was measured by enzyme-linked immunosorbent assay in 100 SLE patients, including 50 patients with current lupus nephritis and 27 patients with current arthritis, as well as in 50 healthy controls. Correlation analysis of serum sclerostin with demography, bone biomarkers, and disease activity in SLE patients was carried out.

RESULTS

Sclerostin levels were significantly elevated in SLE patients, particularly those with lupus nephritis, compared with healthy controls. Higher levels were identified in patients without arthritis compared with those with; however, the former group had more proteinuria and renal impairment. Significant correlations were observed between sclerostin levels and serum creatinine, proteinuria, consumed C3 and C4 complement, and corrected Ca. Using multiple linear regression, proteinuria was the only significant predictor for serum sclerostin in SLE patients.

CONCLUSIONS

This study is the first to report that serum sclerostin is associated with proteinuria in SLE patients and could be used as a valuable biomarker for lupus nephritis.

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.

What is the optimal postoperative sagittal alignment in ankylosing spondylitis patients with thoracolumbar kyphosis following one-level pedicle subtraction osteotomy?

BACKGROUND CONTEXT

Radiographic realignment objectives for the surgical correction of adult spinal deformity (ASD) have been well-described. However, the optimal sagittal spinopelvic alignment after corrective osteotomy for thoracolumbar kyphosis secondary to ankylosing spondylitis (AS) is still unknown so far.

PURPOSE

To comprehensively investigate the relationship between radiographic parameters and clinical outcomes measured by Oswestry Disability Index (ODI) and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) in thoracolumbar kyphosis patients caused by AS following one-level pedicle subtraction osteotomy (PSO) and to determine the optimal sagittal alignment at a minimum of 2-year follow-up.

STUDY DESIGN

A retrospective review of consecutive AS patients from one institution (2006-2016).

PATIENT SAMPLE

One hundred AS-related thoracolumbar kyphosis patients who underwent one-level PSO with a minimum of 2-year follow-up (range, 2-10 years).

OUTCOME MEASURES

Spinopelvic parameters at final follow-up (≥2 years) included thoracic kyphosis, lumbar lordosis, osteotomized vertebra angle, pelvic tilt (PT), sacral slope (SS), pelvic incidence, sagittal vertical axis, spinosacral angle (SSA), T1 pelvic angle (TPA), spinopelvic angle (SPA), and global kyphosis. Clinical outcomes at final follow-up (≥2 years) was evaluated by ODI and BASDAI, and ODI<20 was defined as good clinical outcome.

METHODS

Pre- and postoperative radiographic and clinical outcomes were compared by paired samples t test. The correlation between the postoperative radiographic parameters and clinical outcomes was investigated by Pearson correlation analysis. Linear regression analysis was performed to construct predictive models of the clinically relevant radiographic parameters based on ODI scores and to determine the realignment goals. Multiple stepwise regression analysis was applied to figure out the major radiographic contributors of ODI score at the final follow-up.

RESULTS

In total, 100 AS patients (92 males and 8 females) with a mean age of 34.7±9.5 years (range, 17-63 years) were followed up for 38.6±17.5 months (range, 24-120 months). At the final follow-up, PT and TPA were positively correlated with both ODI and BASDAI score (p<.05). Although SS, SSA, and SPA were negatively associated with the score of ODI (p<.05), and BASDAI was negatively related to SPA (p<.05). Predicting regression models of the clinically-relevant radiographic parameters were built based on the ODI score at the last follow-up.

CONCLUSIONS

Based on the regression models, the optimal sagittal alignment of AS patients satisfying good clinical outcome (ODI<20) at a minimum of 2-year follow-up was: PT<24°, SSA>108°, TPA<22°, and SPA>152°. Realizing the aforementioned realignment goals may contribute to satisfied clinical outcome for AS patients with thoracolumbar kyphosis undergoing one-level PSO.

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.

Evaluation of serum fibroblast growth factor-23 in patients with axial spondyloarthritis and its association with sclerostin, inflammation, and spinal damage

The mechanisms underlying new bone formation in individuals with axial spondyloarthritis (axSpA) remain unclear; however, low levels of sclerostin (SOST) may be associated with development of syndesmophytes in those with ankylosing spondylitis (AS). Expression of fibroblast growth factor-23 (FGF-23), another osteocyte factor, is high in those with osteoporosis and chronic renal failure, but levels in those with axSpA are unknown. To evaluate serum FGF-23 and SOST levels in axSpA patients, and to assess their relationship with inflammation and structural damage. In total, 109 axSpA patients (55 with AS and 54 with non-radiographic axSpA) and 57 healthy control (HC) subjects were included in the analysis. Serum concentrations of FGF-23 and SOST were measured and correlation analysis was performed. The presence of syndesmophytes and the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) were used to assess structural damage. Levels of serum FGF-23 in axSpA patients were significantly higher than those in HCs [median (interquartile range-IQR) FGF-23 level, pg/ml; AxSpA = 144 (82.3-253.2), HC = 107 (63.3-192.8), p = 0.010]; however, there was no difference in SOST levels. FGF-23 levels correlated with the erythrocyte sedimentation rate (ESR) (r = 0.265, p = 0.006) and serum C-reactive protein (CRP) level (r = 0.229, p = 0.010). In the axSpA, SOST levels correlated negatively with mSASSS (r = - 0.283, p = 0.007), whereas those in the AS group correlated negatively with CRP (r = - 0.426, p = 0.001). Serum FGF-23 levels were high in axSpA patients. Increased FGF-23 was associated with inflammation, but not with SOST levels or disease activity. SOST correlated negatively with both inflammation and structural damage.

Increased serum levels of MIC1/GDF15 correlated with bone erosion in spondyloarthritis: A pilot study

INTRODUCTION

To assess the association between growth differentiation factor-15 (GDF15) and radiographic features including bone marrow edema and bone erosion in Spondyloarthritis (SpA).

METHODS

Patients with SpA (n = 120) receiving treatment in the Guangdong General Hospital, China, between August 2012 and December 2016 were retrospectively included. Serum of patients and healthy controls (n = 30) were collected and GDF15 levels were measured using ELISA. Inflammation was assessed by C-reactive protein (CRP), and magnetic resonance imaging (MRI) of the sacroiliac joint using Spondyloarthritis Research Consortium of Canada score and a method of dichotomy to assess fat metaplasia, bone erosion, and ankylosis. Radiographs of the pelvis were scored using the modified New York (mNY) score.

RESULTS

Serum GDF15 levels were higher in SpA patients compared to controls (503.52 ± 222.92 vs. 190.86 ± 104.18 pg/mL, P < .0001). Patients who suffered from bone erosion on MRI had higher levels of GDF15 (525.72 [186.33, 801.62]vs. 428.06 [255.15, 670.98] pg/mL, P = .0375). There was a positive correlation between serum GDF15 and CRP (r = 0.5442, P < .0001). Moreover, GDF15 levels were related to CRP levels (r = 0.5658, P < .0001) in those X-ray scores were III, according to 1984mNY criteria. Receiver operating characteristic (ROC) analysis showed that GDF15 levels above 501.98pg/mL could predict presence of bone erosion on MRI.

CONCLUSION

The present study suggested that serum GDF15 levels are higher in SpA patients than in healthy controls. The GDF15 level was correlated with CRP and may be a surrogate biomarker in bone erosion.

Sclerostin rather than Dickkopf-1 is associated with mSASSS but not with disease activity score in patients with ankylosing spondylitis

OBJECTIVE

To determine the serum levels of Dickkopf-1 (DKK-1) and sclerostin, as well as their correlations with the structural damage assessed by modified stoke ankylosing spondylitis spine score (mSASSS) and the disease activity evaluated by ankylosing spondylitis disease activity score (ASDAS) in patients with ankylosing spondylitis (AS).

METHODS

Eighty-eight AS patients, 26 rheumatoid arthritis (RA) patients, and 26 age- and gender-matched healthy controls (HC) were collected from rheumatic clinic of the Second Affiliated Hospital of Zhejiang University, School of Medicine, between March 2015 and July 2015. Demographic data, parameters of ASDAS, and image evaluations of spine (i.e., mSASSS) were collected. The serum levels of DKK-1 and sclerostin were measured using commercially available ELISA kits.

RESULTS

Both DKK-1 and sclerostin were significantly higher in the AS patients than in the controls (1855 ± 84.58 vs. 1406 ± 99.76 pg/ml and 106 ± 6.75 vs. 62.78 ± 6.39 pmol/l, respectively, P < 0.05). The correlation analysis suggested a negative correlation between serum sclerostin and mSASSS (P = 0.019, r² = 0.062). DKK-1 had a trend of positive correlation with mSASSS, but was not statistically significant (P > 0.05). There was no association between the serum levels of DKK-1 or sclerostin and disease activity assessed by ASDAS (P > 0.05). DKK-1 and sclerostin had a negative correlation (P = 0.013, r² = 0.07).

CONCLUSION

In the present study, the expressions of serum DKK-1 and sclerostin were independent of disease activity. Sclerostin was negatively correlated with the mSASSS, which suggests that sclerostin may be a potential marker indicating the spine ossification process in AS. The specific mechanism remains to be investigated.

Serum CCL11 level is associated with radiographic spinal damage in patients with ankylosing spondylitis

The clinical significance of C-C motif chemokine11 (CCL11) in bone metabolism in ankylosing spondylitis (AS) is not clearly elucidated. Thus, this cross-sectional study aimed to compare serum levels of CCL11 between patients with AS and healthy controls and to investigate the relationship between serum levels of CCL11 and radiographic spinal damage in patients with AS. We consecutively recruited 55 male patients with AS and 26 age- and sex-matched healthy controls. Serum levels of CCL11, tumor necrosis factor-α (TNF-α), interleukin-17, and Dickkopf-1 (DKK-1) were measured with commercially available enzyme-linked immunosorbent assay kits. Radiographs were scored according to the modified Stoke ankylosing spondylitis spine score (mSASSS), and syndesmophytes were defined as mSASSS ≥ 2. The serum levels of CCL11 in AS patients with syndesmophytes were significantly higher than those in AS patients without syndesmophytes (p = 0.007) and healthy controls (p = 0.006). In AS patients, the serum levels of CCL11 were significantly and positively correlated with mSASSS (p = 0.006), number of syndesmophytes (p = 0.029). After adjusting for confounding factors, elevated serum levels of CCL11 were associated with increased mSASSS (β = 0.007, p = 0.03) and higher risk for the presence of syndesmophytes (OR 2.34 per 50 pg/ml increase, p = 0.012) in AS patients. We found that the serum level of CCL11 was associated with structural damage in patients with AS, suggesting that CCL11 may serve as a promising biomarker for new bone formation in AS.

Serum Sclerostin as a Possible Biomarker in Ankylosing Spondylitis: A Case-Control Study

Objective

Several molecules are involved in the pathogenesis of a new bone formation in ankylosing spondylitis (AS). The aim of this study was to evaluate the serum levels of sclerostin in patients with AS as a possible biomarker and to investigate any correlations with radiographic damage, disease activity, and function.

Methods

AS patients fulfilled the modified New York criteria, and healthy controls were enrolled for this study. BASDAI, ASDAS-CRP, BASMI, BASFI, patient and physician VAS, and C-reactive protein were evaluated at baseline visit. Spinal damage was assessed using the mSASSS on radiographs performed within 3 months from baseline. Serum concentrations of sclerostin were assessed at baseline and after four months of therapy in patients who started an anti-TNF.

Results

Twenty healthy subjects and 40 AS patients were enrolled in the study. In our group, serum sclerostin levels (median (25th–75th percentile)) were significantly higher in healthy controls (18.04 (13.6–24) pg/ml) than in AS patients (6.46 (4.5–11.1) pg/ml; P value < 0.01). However, no significant correlations were found between serum sclerostin levels and radiographic damage, assessed by mSASSS, and between serum sclerostin levels and clinical indices of activity and disability or with laboratory parameters. Sclerostin levels did not show significant changes after 4 months of anti-TNF therapy.

Conclusions

The results of our study suggest a possible role of sclerostin in the identification of AS patients. Further studies are needed to prove the role of sclerostin as a disease activity biomarker and progression of disease in AS.

Dickkopf-1 in ankylosing spondylitis: Review and meta-analysis

BACKGROUND

Current findings regarding serum Dickkopf-1 (DKK-1) concentration in ankylosing spondylitis (AS) have proven inconsistent. This meta-analysis was performed to provide a better understanding of serum DKK-1 and AS.

METHODS

Online electronic databases were used to retrieve all relevant articles published before November 2017. The pooled standardized mean difference (SMD) with 95% confidence interval (CI) was calculated by the random-effect model.

RESULTS

23 studies, containing 1348 AS patients and 909 healthy controls, were included in this meta-analysis. No significant difference in serum DKK-1 concentration was found between AS patients and healthy controls (pooled SMD = 0.488, 95%CI = -0.176 to 1.152, p = 0.150). Subgroup analyses suggested that serum DKK-1 in patients with increased C-reactive protein (CRP) (CRP > 10 mg/L) and high modified Stroke AS Spine Score (mSASSS) (mSASSS > 30) were significantly lower than healthy controls. Serum DKK-1 was, however, increased in patients with normal CRP (CRP≤ 10 mg/L).

CONCLUSION

Although serum DKK-1 concentration was not significantly different in AS vs. healthy controls, it may be used as a biomarker of inflammation and radiographic damage in AS.

Sclerostin and Antisclerostin Antibody Serum Levels Predict the Presence of Axial Spondyloarthritis in Patients with Inflammatory Bowel Disease

OBJECTIVE

The early diagnosis of inflammatory bowel disease (IBD)-associated spondyloarthritis (SpA/IBD) in patients affected by IBD represents a major topic in clinical practice; in particular, to date there are no available serum biomarkers revealing the presence of joint inflammation in these patients. Sclerostin (SOST), an antagonist of the Wnt/β-catenin pathway, and antisclerostin-immunoglobulin G (anti-SOST-IgG) have been recently studied in patients with ankylosing spondylitis (AS) as a putative marker of disease activity.

METHODS

SOST and anti-SOST-IgG serum levels were assayed in 125 patients with IBD, 85 with axial or peripheral SpA, and in control groups (patients with AS and rheumatoid arthritis, and healthy individuals). The diagnostic performance in discriminating the presence of SpA/IBD was assessed for both candidate biomarkers.

RESULTS

Patients affected by SpA/IBD with axial involvement displayed significantly lower levels of SOST and higher levels of anti-SOST-IgG compared to patients with only peripheral arthritis, IBD, and controls. Moreover, SOST and anti-SOST-IgG serum levels were inversely correlated and were associated with the duration of articular symptoms. Both biomarkers showed good accuracy in predicting the presence of axial SpA in patients with IBD.

CONCLUSION

We demonstrated that in patients with IBD, SOST and anti-SOST-IgG might represent novel biomarkers to assess the presence of axial joint involvement. Moreover, the development of anti-SOST-IgG and the subsequent decrease of SOST serum levels could play a role in the pathogenesis of SpA/IBD.

Crosstalk between MLO-Y4 osteocytes and C2C12 muscle cells is mediated by the Wnt/β-catenin pathway

We examined the effects of osteocyte secreted factors on myogenesis and muscle function. MLO-Y4 osteocyte-like cell conditioned media (CM) (10%) increased ex vivo soleus muscle contractile force by ~25%. MLO-Y4 and primary osteocyte CM (1-10%) stimulated myogenic differentiation of C2C12 myoblasts, but 10% osteoblast CMs did not enhance C2C12 cell differentiation. Since WNT3a and WNT1 are secreted by osteocytes, and the expression level of Wnt3a is increased in MLO-Y4 cells by fluid flow shear stress, both were compared, showing WNT3a more potent than WNT1 in inducing myogenesis. Treatment of C2C12 myoblasts with WNT3a at concentrations as low as 0.5ng/mL mirrored the effects of both primary osteocyte and MLO-Y4 CM by inducing nuclear translocation of β-catenin with myogenic differentiation, suggesting that Wnts might be potential factors secreted by osteocytes that signal to muscle cells. Knocking down Wnt3a in MLO-Y4 osteocytes inhibited the effect of CM on C2C12 myogenic differentiation. Sclerostin (100ng/mL) inhibited both the effects of MLO-Y4 CM and WNT3a on C2C12 cell differentiation. RT-PCR array results supported the activation of the Wnt/β-catenin pathway by MLO-Y4 CM and WNT3a. These results were confirmed by qPCR showing up-regulation of myogenic markers and two Wnt/β-catenin downstream genes, Numb and Flh1. We postulated that MLO-Y4 CM/WNT3a could modulate intracellular calcium homeostasis as the trigger mechanism for the enhanced myogenesis and contractile force. MLO-Y4 CM and WNT3a increased caffeine-induced Ca²⁺ release from the sarcoplasmic reticulum (SR) of C2C12 myotubes and the expression of genes directly associated with intracellular Ca²⁺ signaling and homeostasis. Together, these data show that in vitro and ex vivo, osteocytes can stimulate myogenesis and enhance muscle contractile function and suggest that Wnts could be mediators of bone to muscle signaling, likely via modulation of intracellular Ca²⁺ signaling and the Wnt/β-Catenin pathway.

Results from Polish Spondyloarthritis Initiative registry (PolSPI) - methodology and data from - the first year of observation

OBJECTIVES

Report on one-year results from the Polish Spondyloarthritis Initiative registry (PolSPI), containing the cross-sectional analysis of clinical and imaging data as well as database methodology.

MATERIAL AND METHODS

The PolSPI registry includes patients with axial (axSpA) and peripheral (perSpA) spondyloarthritis according to ASAS classification criteria, and/or patients with ankylosing spondylitis according to modified New York criteria, psoriatic arthritis according to CASPAR criteria, arthropathy in inflammatory bowel disease, reactive arthritis, juvenile spondyloarthritis or undifferentiated spondyloarthritis. Epidemiologic data and history of signs, symptoms and treatment of spondyloarthritis are collected and assessment of disease activity is performed. Radiographic images of sacroiliac joint, cervical and lumbar spine, and results of bone densitometry are collected. Every 6 months blood samples for inflammatory markers, and for long-term storage are taken.

RESULTS

During a one-year period from September 2015 to August 2016, 63 patients were registered on an electronic database; 44 (69.8%) of patients were classified as axial spondyloarthritis (axSpA) and 19 (30.2%) as peripheral spondyloarthritis (perSpA) according to ASAS criteria. Statistically significant differences between axSpA and perSpA were discovered in the percentage of HLA-B27 antigen occurrence (92.6% and 50%, respectively), BASDAI (2.8% and 4.1%, respectively), DAS 28 (2.66% and 4.03%, respectively), percentage of peripheral arthritis (20% and 88.8%, respectively), enthesitis (26.7% and 70.6%, respectively), dactylitis (6.7% and 88.9%, respectively), as well as extra-articular symptoms: acute anterior uveitis (26.7% and 5.6%, respectively) and psoriasis (6.9% and 55.6%, respectively). Patients with axSpA had significantly higher mean grade of sacroiliac involvement according to New York criteria, higher mSASSS score, and lower T-score in femoral neck in bone densitometry.

CONCLUSIONS

At the early stage of the disease patients with axSpA compared to those with perSpA, have more advanced structural damage of sacroiliac joints and spine, and lower bone mineral density in the femoral neck. In the upcoming years the PolSPI registry will prospectively follow-up patients with SpA, recording response to treatment and carrying out research on interaction of inflammation and bone remodelling.

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.

Pathogenesis of ligaments ossification in spondyloarthritis: insights and doubts

Despite intensive research in spondyloarthritis pathogenesis, some important questions still remain unanswered, particularly concerning enthesis new bone formation. Several evidences suggest that it prevalently occurs by endochondral ossification, however it remains to identify factors that can induce and influence its initiation and progression. Recent progress, achieved in animal models and in vitro and genetic association studies, has led us to hypothesize that several systemic factors (adipokines and gut hormones) and local factors (BMP and Wnt signaling) as well as angiogenesis and mechanical stress are involved. We critically review and summarize the available data and delineate the possible mechanisms involved in enthesis ossification, particularly at spinal ligament level. KEY MESSAGES Complete understanding of spondyloarthritis pathophysiology requires insights into inflammation, bone destruction and bone formation, which are all located in entheses and lead all together to ankylosis and functional disability. Several factors probably play a role in the pathogenesis of bone formation in entheses including not only cytokines but also several systemic factors such as adipokines and gut hormones, and local factors, such as BMP and Wnt signaling, as well as angiogenesis and mechanical stress. Data available about pathophysiology of new bone formation in spondyloarthritis are limited and often conflicting and future studies are needed to better delineate it and to develop new therapeutic approaches.

Sclerostin measurement in human disease: Validity and current limitations

Sclerostin a potent regulator of bone formation, is an antagonist of the Wnt-signaling pathway. The advent of assays to measure circulating sclerostin has enabled research to be performed with the aim to understand the potential role of circulating sclerostin as a pathophysiological marker in a variety of clinical settings. At this time, however, assays to measure circulating sclerostin are still relatively new and have not demonstrated consistent internal agreement in addition to which there are differences between serum and plasma levels. Nevertheless, measurement of sclerostin in the circulation has the potential to reflect the dynamics of bone formation with particular reference to situations in which osteocytes, the major source of circulating sclerostin, may be perturbed. Because of technical uncertainties regarding sclerostin assays that are currently available, circulating sclerostin measurements should be interpreted cautiously with attention to reference ranges for each assay and whether or not the measurement is made in serum or plasma.

Serum prolidase level in ankylosing spondylitis: low serum levels as a new potential gold standard biomarker for disease activity

Ankylosing spondylitis (AS) is a chronic inflammatory disorder that mainly affects the sacroiliac joints and axial skeleton. The aim of this study was to assess serum prolidase level (SPL) and its association with disease activity in patients with AS. This prospective study included 75 AS patients. Thirty age- and gender-matched healthy controls were enrolled. AS patients were considered as active if BASDAI score was ≥4 or inactive if BASDAI score was <4. There were 34 AS patients in the active group and 41 AS patients in the inactive group. Anti-TNF-monoclonal antibody treatment was started in patients in the active group. These active patients were reassessed 6 months later. BASDAI, ASDAS, visual analogue scale, short-form-general health survey questionnaire, C-reactive protein, erythrocyte sedimentation rate and SPL were measured in all AS patients before and after treatment. The SPL was significantly lower in inactive AS patients than in control group, and also, SPL was significantly lower in active AS patients than in inactive patients. All activity parameters were successful in separating active and inactive AS patients. However, the only parameter that could distinguish active patients from inactive patients was prolidase. The optimum cutoff point of SPL to identify patients with active AS was 23.13 ng/mL with sensitivity, specificity, positive predictive value and negative predictive value of 100 %. Serum prolidase level was successful in measuring disease activity and had as high sensitivity and specificity as BASDAI and was superior to other activity parameters.

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.

Association between serum dickkopf-1 levels and disease duration in axial spondyloarthritis

BACKGROUND

Axial spondyloarthritis (axSpA) is characterized by new bone formation. The complex systems underlying this process involve Wnt-signaling pathway. It has been observed that serum levels of dickkopf-1 (DKK-1), an important inhibitor of Wnt-signaling, are decreased in patients with axSpA. However, these data are from studies including only patients with long-standing disease. The aim of this study is to investigate if symptom duration influences on serum DKK-1 levels in patients with axSpA.

MATERIAL AND METHODS

A cross-sectional study including consecutive patients with axSpA (ASAS criteria) naïve for anti-TNF therapy. Collected data included demographic and disease characteristics, time since first symptom onset, assessment of disease activity and function, and determination of DKK-1 serum levels. Patients were classified as early axSpA (symptom duration ≤5 years) and established axSpA (>5 years). Linear regression models were employed to investigate the variables related to DKK-1 serum levels.

RESULTS

In total, 90 patients were included. Sixty-eight patients had early axSpA and 22 had established disease. Serum levels of DKK-1 were significantly higher in patients with early axSpA compared with established axSpA (22.1±12.6 vs 16.4±10.7pM; p=0.04). Among all tested variables, only symptom duration was significantly and inversely correlated with DKK-1 serum levels (beta: -0.041; p=0.01).

CONCLUSION

Serum DKK-1 levels in axSpA depend on disease duration. As disease duration increases, DKK-1 serum levels decrease. Based on this, an intensive treatment at early stages of the disease could have a better outcome on inhibiting/slowing radiographic progression in patients with axSpA.

How Accurate is Your Sclerostin Measurement? Comparison Between Three Commercially Available Sclerostin ELISA Kits

Sclerostin, bone formation antagonist is in the spotlight as a potential biomarker for diseases presenting with associated bone disorders such as chronic kidney disease (CDK-MBD). Accurate measurement of sclerostin is therefore important. Several immunoassays are available to measure sclerostin in serum and plasma. We compared the performance of three commercial ELISA kits. We measured sclerostin concentrations in serum and EDTA plasma obtained from healthy young (18-26 years) human subjects using kits from Biomedica, TECOmedical and from R&D Systems. The circulating sclerostin concentrations were systematically higher when measured with the Biomedica assay (serum: 35.5 ± 1.1 pmol/L; EDTA: 39.4 ± 2.0 pmol/L; mean ± SD) as compared with TECOmedical (serum: 21.8 ± 0.7 pmol/L; EDTA: 27.2 ± 1.3 pmol/L) and R&D Systems (serum: 7.6 ± 0.3 pmol/L; EDTA: 30.9 ± 1.5 pmol/L). We found a good correlation between the assay for EDTA plasma (r > 0.6; p < 0.001) while in serum, only measurements obtained using TECOmedical and R&D Systems assays correlated significantly (r = 0.78; p < 0.001). There was no correlation between matrices results when using the Biomedica kit (r = 0.20). The variability in values generated from Biomedica, R&D Systems and TECOmedical assays raises questions regarding the accuracy and specificity of the assays. Direct comparison of studies using different kits is not possible and great care should be given to measurement of sclerostin, with traceability of reagents. Standardization with appropriate material is required before different sclerostin assays can be introduced in clinical practice.

Serum DKK-1 level in the development of ankylosing spondylitis and rheumatic arthritis: a meta-analysis

To explore the association of serum Dickkopf-1 (DKK-1) levels with the development of ankylosing spondylitis (AS) and rheumatic arthritis (RA) in humans, databases including PubMed, EBSCO, Springerlink, Ovid, WANFANG and China National Knowledge Infrastructure (CNKI) were searched to identify relevant studies. On the basis of rigorous inclusion and exclusion criteria, case–control studies of the relationships between serum DKK-1 levels and AS and RA published before December 2014 were enrolled. Statistical analyses were performed using Comprehensive Meta-analysis 2.0 (CMA 2.0). Seven case–control trials with a total of 300 AS patients, 136 RA patients and 232 healthy controls were included in this study. Meta-analysis results revealed that DKK-1 serum levels were significantly higher in AS patients than in normal controls (standard mean differences (s.m.d.)=0.301, 95% confidence interval (CI)=0.094–0.507, P=0.004), whereas no significant difference in DKK-1 serum levels was observed between RA patients and healthy controls (s.m.d.=0.798, 95% CI=−2.166–3.763, P=0.598). Serum DKK-1 level may be closely related to the development of AS but not of RA.

Sclerostin serum levels in patients with systemic autoimmune diseases

Systemic autoimmune diseases (SADs) are associated with lower bone mass and an increased risk of fractures. Sclerostin has a pivotal role in bone metabolism. Available data on circulating sclerostin levels in healthy subjects are limited, whereas those in SAD patients are absent. Our objective was to determine circulating sclerostin concentrations in systemic lupus erythematosus (SLE), systemic sclerosis (SSc) and Crohn's disease (CD) patients, and to analyze the factors associated with sclerostin concentrations. In this cross-sectional case-control study, serum sclerostin levels were measured in 38 SLE patients, 20 CD patients, 8 SSc patients and 20 healthy controls using a sclerostin ELISA. The mean values of the sclerostin (95% confidence interval) were 35.36 pmol l(-1) (12-101) in patients and 33.92 pmol l(-1) (2.31-100) in control subjects. The mean sclerostin value was 36.4 pmol l(-1) (22.1-48.5) in SLE patients, 26.7 pmol l(-1) (17.3-36.3) in CD patients and 51.8 pmol l(-1) (26.5-77.1) in SSc patients (P=0.001). Serum sclerostin levels were positively correlated with age (P<0.001), body mass index (BMI) (P=0.01) and lumbar spine Z-score (P=0.001) and negatively with creatinine clearance (P=0.001). Glucocorticoid treatment did not affect sclerostin levels. Sclerostin levels seem to have a heterogeneous pattern in different autoimmune diseases. SLE and SSc patients did not differ from healthy controls regarding sclerostin levels. The CD group had significantly lower values compared with SSc patients. Factors associated with sclerostin levels in autoimmune diseases seem to be the same than in the general population.

Treatment of a mouse model of ankylosing spondylitis with exogenous sclerostin has no effect on disease progression

Background

No treatment to date is available which specifically targets bone formation in ankylosing spondylitis (AS). Several recent studies have shown that sclerostin (SOST), a Wnt inhibitor specific to osteocytes and chondrocytes, is down-regulated in AS patients. This suggests Wnt signalling may be upregulated, and application of exogenous recombinant SOST (rSOST) may inhibit Wnt signalling and slow pathological bone formation.

Methods

The proteoglycan-induced spondylitis (PGISp) mouse model in which we have previously demonstrated downregulated SOST expression, was used for this study. Mice were injected with 2.5ug rSOST/day for a period of 8 weeks following induction of disease. Axial skeleton disease development was assessed by histology and skeletal changes examined using DEXA.

Results

rSOST treatment had no effect on peripheral or axial disease development, bone density or disease severity. Injected rSOST was stable over 8 h and residual levels were evident 24 h after injection, resulting in a cumulative increase in SOST serum levels over the treatment time course. Immunohistochemical examination of SOST levels within the joints in non-rSOST treated PGISp mice showed a significant decrease in the percentage of positive osteocytes in the unaffected joints compared to the affected joints, while no difference was seen in rSOST treated mice. This suggests that rSOST treatment increases the number of SOST-positive osteocytes in unaffected joints but not affected joints, despite having no impact on the number of joints affected by disease.

Conclusions

Although not disease-modifying, rSOST treatment did appear to regulate SOST levels in the joints suggesting biological activity. Further dose response studies are required and SOST may require modifications to improve its bone targeting ability in order to affect tissue formation to a meaningful level in this model.

Biomarkers for diagnosis, monitoring of progression, and treatment responses in ankylosing spondylitis and axial spondyloarthritis

With the growing awareness of the impact of chronic back pain and axial spondyloarthritis and recent breakthroughs in genetics and the development of novel treatments which may impact best on early disease, the need for markers that can facilitate early diagnosis and profiling those individuals at the highest risk for a bad outcome has never been greater. The genetic basis of ankylosing spondylitis has been considerably advanced, and HLA-B27 testing has a role in the diagnosis. Knowledge is still incomplete of the rest of the genetic contribution to disease susceptibility, and it is likely premature to use extensive genetic testing (other than HLA-B27) for diagnosis. Serum and plasma biomarkers have been examined extensively in assessing disease activity, treatment response, and as predictors or radiographic severity. For assessing disease activity, other than C-reactive protein and erythrocyte sedimentation rate, the most work has been in examining cytokines (particularly interleukin 17 and 23), matrix metalloproteinase (MMP) markers (particularly MMP3). For assessing those at the highest risk for radiographic progression, biomarkers of bony metabolism, cartilage and connective tissue degradation products, and adipokines have been most extensively assessed. The problem is that no individual biomarkers has been reproducibly shown to assess disease activity or predict outcome, and this area still remains an unmet need, of relevance to industry stakeholders, to regulatory bodies, to the healthcare system, to academic investigators, and finally to patients and providers.

The relationships between serum sclerostin, bone mineral density, and vascular calcification in rheumatoid arthritis

CONTEXT

Recent data indicate that the secreted glycoprotein sclerostin may be involved in vascular calcification (VC).

OBJECTIVE

The objective of the study was to establish whether serum sclerostin levels are associated with VC in patients with rheumatoid arthritis (RA).

DESIGN

This was a cross-sectional study.

SETTING

The study was conducted with ambulatory care.

PATIENTS

We compared 75 RA patients with 75 age- and gender-matched control participants.

INTERVENTION

Coronary artery calcification (CAC) and abdominal aortic calcification (AAC) scores were evaluated by computed tomography.

MAIN OUTCOME MEASURE

Serum sclerostin levels (determined with an ELISA) were assessed. A statistical analysis was performed to identify the determinants of serum sclerostin and VC.

RESULTS

AAC and CAC were more prevalent and more severe in patients with RA than in controls. Higher levels of AAC (P = .02) and a higher lumbar bone mineral density (BMD; P = .03) were identified as independent determinants of higher serum sclerostin levels in RA patients, whereas male gender (P = .03), higher lumbar BMD (P < .0001), and low estimated glomerular rate (P < .001) were identified as determinants in controls. In RA patients, a multivariate logistic regression analysis indicated that older age [P < .01, with an odds ratio (OR) per year 1.10] and male gender (P = .02, OR 6.79) were independent determinants of CAC and that older age (P < .001, OR 1.16) were independent determinants of AAC. In controls, the independent determinants were older age (P < .01, OR 1.19), hypertension (P < .01, OR 7.31), and lumbar BMD (P = .03, OR per 30 mg/cm(2) increment of 1.14) for CAC and older age (P = .01, OR 1.11) for AAC.

CONCLUSIONS

Serum sclerostin levels were significantly and independently associated with AAC in RA patients.

Fetuin-A is related to syndesmophytes in patients with ankylosing spondylitis: a case control study

OBJECTIVES

New bone formation is one of the hallmark characteristics of ankylosing spondylitis, which is thereby associated with syndesmophytes. Fetuin-A is a molecule that is abundantly found in calcified tissues and it shows high affinity for calcium phosphate minerals and related compounds. Considering the role of fetuin-A in the regulation of calcified matrix metabolism, we compared the fetuin-A levels in ankylosing spondylitis patients with syndesmophytes with those in patients without syndesmophytes and in healthy controls. We also studied other biomarkers that are thought to be related to syndesmophytes.

METHODS

Ninety-four patients (49 patients without syndesmophytes, 67.3% male, 40.7±8.7 years; 45 patients with syndesmophytes, 71.1% M, 43.9±9.9 years) and 68 healthy controls (44.2±10.6 years and 70.6% male) were included in this study. Syndesmophytes were assessed on the lateral radiographs of the cervical and lumbar spine. The serum levels of fetuin-A, dickkopf-1, sclerostin, IL-6, high-sensitivity C-reactive protein and bone morphogenetic protein-7 were measured with an enzyme-linked immunosorbent assay.

RESULTS

Patients with syndesmophytes had significantly higher levels of fetuin-A compared with patients without syndesmophytes and controls (1.16±0.13, 1.05±0.09 and 1.08±0.13 mg/ml, respectively). However, fetuin-A was not different between the patients without syndesmophytes and controls. Bone morphogenetic protein-7 was significantly lower; dickkopf-1 was significantly higher in patients with ankylosing spondylitis compared with controls. The sclerostin concentrations were not different between the groups. In regression analysis, fetuin-A was an independent, significant predictor of syndesmophytes.

CONCLUSION

Our results suggest that fetuin-A may a role in the pathogenesis of bony proliferation in ankylosing spondylitis.

Circulating periostin levels in patients with AS: association with clinical and radiographic variables, inflammatory markers and molecules involved in bone formation

OBJECTIVE

The aim of this study was to evaluate serum periostin levels in patients with AS in comparison with healthy controls as well as their association with clinical, inflammatory and radiographic parameters and molecules involved in bone formation.

METHODS

Serum samples for periostin, total Dickkopf-1 (Dkk-1), sclerostin, VEGF and inflammatory markers were obtained from 65 TNF inhibitor-naive patients with AS. The BASDAI, BASFI, modified Stoke AS Spine Score and BASRI for the spine (BASRI-s) were assessed for each patient. Serum periostin levels were also measured in 36 sex-, age- and BMI-matched controls.

RESULTS

Serum periostin levels were significantly lower in AS patients compared with controls [234.4 pg/ml (s.e.m. 7.5) vs 291.4 (s.e.m. 8.3), respectively; P < 0.001]. Periostin levels were higher in AS patients with elevated CRP (P = 0.005), high BASDAI (P = 0.014) and low BASRI-s (P = 0.033) and were correlated with BMI (r = -0.304, P = 0.014), ESR (r = 0.395, P = 0.001), CRP (r = 0.413, P = 0.001), BASRI-s (r = -0.242, P = 0.047) and sclerostin (r = -0.280, P = 0.024). In multiple regression analysis, periostin levels were an independent variable of CRP (β = 0.160, P = 0.009) and sclerostin levels (β = -0.311, P = 0.012).

CONCLUSION

Our data suggest that periostin levels are low in patients with AS. Among AS patients, periostin levels are higher in those with higher disease activity, higher systemic inflammation and less extensive radiographic damage. Periostin is independently associated with CRP and sclerostin levels.

Plasma and synovial fluid sclerostin are inversely associated with radiographic severity of knee osteoarthritis

OBJECTIVE

The purpose of this study was to analyze sclerostin in plasma and synovial fluid of knee osteoarthritis (OA) patients and to investigate the association between sclerostin levels and radiographic severity.

DESIGN AND METHODS

A total of 190 subjects (95 knee OA patients and 95 healthy controls) were recruited in the present study. Sclerostin levels in plasma and synovial fluid were assessed using an enzyme-linked immunosorbent assay. OA grading was performed using the Kellgren-Lawrence classification.

RESULTS

Plasma sclerostin levels were significantly lower in OA patients than in healthy controls (P=0.004). Additionally, sclerostin levels in plasma were significantly higher with respect to paired synovial fluid (P<0.001). Moreover, sclerostin levels in plasma and synovial fluid demonstrated a significant inverse correlation with the radiographic severity of knee OA (r=-0.464, P<0.001 and r=-0.592, P<0.001, respectively). Subsequent analysis revealed that there was a positive correlation between plasma and synovial sclerostin levels (r=0.657, P<0.001).

CONCLUSIONS

Sclerostin was significantly lower in OA plasma samples when compared with healthy controls. Plasma and synovial fluid sclerostin levels were inversely associated with the radiographic severity of knee OA. Therefore, sclerostin may be utilized as a biochemical marker for reflecting disease severity in primary knee OA.