Sclerostin rather than Dickkopf-1 is associated with mSASSS but not with disease activity score in patients with ankylosing spondylitis. Clin Rheumatol. 2019;38:989-995. [PMID: 30443790 DOI: 10.1007/s10067-018-4356-z]

The serum level of sclerostin decreases in radiographic axial spondyloarthritis patients with fatty lesions

BACKGROUND

Currently, the pathophysiology of new bone formation in radiographic axial spondyloarthritis (r-axSpA) remains unclear. Cellular elements and their secreted bone turnover markers might be one of the underlying mechanisms that drive the new bone formation. Our study aimed to investigate the role of bone turnover markers in r-axSpA patients with fatty lesions.

METHODS

73 r-axSpA patients were enrolled in this study. 48 and 25 patients were divided into r-axSpA group with and without fatty lesions. Clinical variables were collected and all patients received comprehensive rheumatologic assessment for disease activity, including Modified Stoke Ankylosing Spondylitis Spine Score (mSASSS), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Axial Spondyloarthritis Disease Activity Score (ASDAS). Fatty lesions in the sacroiliac joints (SIJs) were scored independently by two radiologists. Serum levels of bone turnover markers, including sclerostin, osteoprotegerin (OPG), procollagen I N-terminal propeptide (PINP), cross linked C-telopeptide of type I collagen (CTX-I), osteocalcin (OC), were measured using enzyme-linked immunosorbent assays.

RESULTS

There were no significant differences between two groups in terms of gender, age, body mass index (BMI), duration, smoking, HLA-B27 positivity rate, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), BASDAI, ASDAS-ESR, ASDAS-CRP, biological disease-modifying anti-rheumatic drugs (bDMARDs) rate. No significant differences were observed in terms of OPG, PINP, CTX-I or OC between two groups. The mSASSS were higher in fatty lesions group than in those without fatty lesions (p < 0.001). The serum sclerostin levels were significantly lower in r-axSpA patients with fatty lesions than in those without fatty lesions (p < 0.001). There were correlations between BMI, mSASSS and sclerostin with the comprehensive Berlin scoring method (CBM) scores in the univariate analysis (ρ = 0.311, ρ = 0.306, ρ = -0.920, respectively). However, only sclerostin had correlation with the CBM scores in multivariate analysis (ρ = -0.040, p < 0.001).

CONCLUSIONS

In the r-axSpA patients with fatty lesions, serum sclerostin levels are declined. Serum sclerostin might be useful as a biomarker to predict the progression of the chronic inflammation in SIJs in r-axSpA.

A guideline on biomarkers in the diagnosis and evaluation in axial spondyloarthritis

Objective

To develop a guideline for selecting biomarkers in the diagnosis and assessment in patients with axial spondyloarthritis (axSpA).

Method

A joint effort was carried out by the core team, the literature review team and the multidisciplinary voting panel to formulate recommendations regarding biomarkers in axSpA, using an evidence-based and consensus-based strategy. Certainty of evidence and strength of recommendation were determined, and levels of agreement within the voting panel were calculated.

Results

A total of 20 recommendations were formulated in this guideline, with levels of agreement ranging from 6.48 to 9.71. The two strong recommendations, HLA-B27 testing in patients suspected of axSpA and regular-interval monitoring of CRP/ESR represent the status quo of axSpA evaluation, while the 13 conditional recommendations represent the promising biomarkers with clinical utility in diagnosis, disease activity assessment, prediction of radiographic progression and therapeutic responses. This guideline does not dictate clinical choices of tests on axSpA, and decisions should be made based on comprehensive consideration of costs, accessibility, patients' values and willingness as well as the objective of testing in the local context.

Conclusion

This guideline addresses the interpretation of the clinical significance of biomarkers in axSpA, and the biomarkers endorsed in this guideline composed a clinical toolkit for healthcare professionals to choose from.

Serum concentration of dickkopf-related protein 1 (DKK1) in psoriatic arthritis in the context of bone remodelling

Psoriatic arthritis (PsA) is a chronic inflammatory disease, characterised by the pathological occurrence of two opposite phenomena-osteoresorption and osteogenesis. Dickkopf-related protein 1 (DKK1) which inhibits the Wingless protein (Wnt) signalling pathway has been shown to be a master regulator of bone remodeling in inflammatory rheumatic diseases. However, the exact relationship between DKK1 serum level and bone remodelling is not clear. The goal of this study is to review state-of-the-art knowledge on the association of serum DKK1 with a bone remodelling in PsA. The MEDLINE-PubMed, EMBASE, Scopus, Web of Science and DOAJ databases were searched for appropriate papers. The English terms: 'DKK1', 'Dickkopf-1' 'Dickkopf related protein 1', 'psoriatic arthritis' and 'PsA' were used for search purposes. Eight original articles and two reviews were identified up to August 2023. In four out of 8 discussed studies DKK1 serum level was higher in PsA patients than in healthy controls [Dalbeth, p < 0.01; Diani, p < 0.001; Chung, p < 0.01; Abd el Hamid, p < 0.001)], it was comparable in another (Daousiss, p = 0.430) and was lower in two (Fassio2017, p < 0.05; Fassio2019, p < 0.05). In one study, the comparative groups included patients with axial spondyloarthritis, where DKK1 serum levels were lower in PsA groups [Jadon, peripheral PsA, p = 0.01]. The true relative serum concentration of DKK1 in PsA, as well as its influence on osteogenesis and osteoresorption, is still equivocal. Further studies on this matter with consistent and stringent methodology are warranted.

The plasma levels of Dickkopf-1 elevated in patients with Juvenile Idiopathic Arthritis

BACKGROUND

To explore the role of two major inhibitors of Wnt signal pathway, Dickkopf-1(DKK-1) and Sclerostin (SOST), in the pathogenesis of juvenile idiopathic arthritis (JIA).

METHODS

88 patients with JIA, which including 49 patients with enthesitis-related arthritis (ERA), 21 oligoarthritis (oJIA) and 18 polyarthritis (pJIA), and 36 age-and sex-matched children as healthy controls (HC) were enrolled in this study. The plasma levels of DKK-1 and SOST, measured using commercially available ELISA kits, were analyzed the correlation between the levels of DKK-1/SOST and JIA, and were analyzed in 14 patients with JIA during before and after treatment.

RESULTS

Plasma levels of DKK-1 were significantly higher in the patients with JIA than that in HC, the elevation of DKK-1 level was positively correlated with HLA-B27 positive JIA. DKK-1 levels dropped significantly in patient with JIA after treatment (P < 0.05). There was no significant change in SOST levels among different subtypes of JIA, patients with JIA during before and after treatment, and HC.

CONCLUSION

It was suggested that the DKK-1 may have a certain correlation with the pathogenesis of JIA, and DKK-1 levels are more closely related to the HLA-B27 positive-ERA.

IMPACT

The abnormally elevated levels of Dickkopf-1 (DKK-1) may be involved in the pathogenesis of juvenile idiopathic arthritis (JIA). DKK-1 levels were more closely related to the HLA-B27 positive-enthesitis-related arthritis (ERA). DKK-1 is an inhibitor of Wnt signaling pathway that promotes osteoblastic new bone formation; it is very rare for pediatric patients with HLA-B27 positive-ERA to manifest typical spondylitis, while sacroiliac arthritis is relatively common, which may be related to the high levels of DKK-1, which is consistent with the early stage of ankylosing spondylitis (AS).

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.

Increased circulating sclerostin levels in rheumatoid arthritis patients: an updated meta-analysis

BACKGROUND

Sclerostin, a regulator of bone metabolism and vascular calcification involved in regulating the Wnt/β-catenin signaling pathway, has been shown to be involved in the pathogenesis of rheumatoid arthritis (RA). However, current results regarding the circulating sclerostin level of RA patients are debatable. This study aimed to evaluate the circulating level of sclerostin in RA patients and briefly summarize its role.

METHOD

PubMed, EMBASE, and the Cochrane Library databases were systematically searched till May 27, 2021, for eligible articles. Useful data from all qualified papers were systematically extracted and analyzed using Stata 12.0 software (Stata Corp LP, College Station, TX, USA).

RESULTS

Overall, 13 qualifying studies including 1030 cases and 561 normal controls were analyzed in this updated meta-analysis. Forest plot of this meta-analysis showed that RA patients had higher circulating sclerostin levels (P < 0.001, standardized mean difference [SMD] = 0.916, 95% CI: 0.235-1.597) compared to normal controls. Subgroup analyses implied that age, region, and assay method were associated with sclerostin level in RA patients.

CONCLUSION

RA patients have higher circulating sclerostin levels, and these was influenced by age, region, and assay method.

Effect of Warming Yang, Tonifying Kidney, and Removing Arthralgia Therapy on Cold-Dampness Arthralgia Type Ankylosing Spondylitis and Its Influence on the Levels of Humoral Factor in Human Serum

Objective

This study is aimed at exploring the effect of warming Yang, tonifying kidney, and removing arthralgia therapy in the treatment of cold-dampness arthralgia type ankylosing spondylitis (AS) and the effects on the levels of humoral factor in human serum. Method. A total of 72 patients with cold-dampness arthralgia type AS treated in our hospital from May 2020 to June 2021 were selected and divided into the observation group (n = 36) and control group (n = 36) according to the random number table method. The clinical efficacy of the two groups was observed. The traditional Chinese medicine (TCM) syndrome scores and clinical signs of the two groups were compared, and the pain situation of the two groups was evaluated by visual analog scale (VAS). Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Bath Ankylosing Spondylitis Functional Index (BASFI) were used to evaluate the spinal function and activity of the two groups, and the levels of CXC-type chemokine ligand 16 (CXCL16), Dickkopf-1(DKK-1), interleukin-17 (IL-17), tumor necrosis factor-α (TNF-α), sclerostin (SOST) ,and bone morphogenetic protein 2(BMP-2) in serum of the two groups were measured.

Results

The total effective rate of the observation group (91.67%) was significantly higher than that of the control group (66.67%) (P < 0.05). After treatment, the degree of improvement in TCM syndrome score, clinical signs, VAS score, BASDAI, BASFI, and the levels of CXCL16, TNF-α, IL-17, DKK-1, SOST, and BMP-2 in the observation group were significantly higher than that in the control group (all P < 0.05). Conclusion. Warming Yang, tonifying kidney, and removing arthralgia therapy had a good effect on the treatment of cold-dampness arthralgia type AS, and it could effectively improve the clinical symptoms and signs, relieve pain, improve spinal motion, and relieve inflammation of patients.

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 comparison of effects of balneotherapy, water-based and land-based exercises on disease activity, symptoms, sleep quality, quality of life and serum sclerostin level in patients with ankylosing spondylitis: A prospective, randomized study

Objectives

This study aims to compare the effects of balneotherapy, water-based exercise (WBE), and land-based exercise (LBE) on disease activity, symptoms, sleep quality, quality of life, and serum sclerostin level (SSL) in patients with ankylosing spondylitis (AS).

Patients and methods

Between January 2019 and January 2020, a total of 60 patients (35 males, 25 females; mean age: 40.9±11.2 years; range, 18 to 55 years) who were diagnosed with AS were randomly divided into the balneotherapy (n=20), WBE (n=20), and LBE (n=20) groups (20 sessions of treatment in groups of five to six patients). The patients were evaluated before treatment and at 4 and 12 weeks using the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), Ankylosing Spondylitis Disease Activity Score-C-reactive protein (ASDAS-CRP), Maastricht Ankylosing Spondylitis Enthesitis Score (MASES), Ankylosing Spondylitis Quality of Life (ASQoL) Scale, Fatigue Severity Scale (FSS), and Pittsburg Sleep Quality Index (PSQI), and SSL were measured.

Results

Statistically significant improvements in the BASDAI, BASFI, MASES, BASMI, ASQoL, FSS, and ASDAS-CRP scores were observed in all groups at 4 and 12 weeks of follow-up (p<0.05). A significant improvement in sleep latency was seen in the balneotherapy and WBE groups. Changes in SSL were not statistically significant in any group (p>0.05).

Conclusion

Balneotherapy, WBE, and LBE are effective in the treatment of AS, and the beneficial effects may last for at least 12 weeks.

Biomarkers in axial spondyloarthritis and low back pain: a comprehensive review

The spectrum of axial spondyloarthritis (AxSpA) (including both non-radiographic and radiographic AxSpA), also known as ankylosing spondylitis AS, has achieved growing recognition. With the development of treatments not only effective in controlling disease activity but also in slowing radiographic progression, and given the cost and risk profiles of these novel treatments and the limitations of current clinical criteria, imaging and peripheral blood biomarkers (C-reactive protein, HLA-B27 testing), the need for better biomarkers has never been greater. The purpose of this review is to present up-to-date information on the biomarkers for the diagnosis for assessing disease diagnosis, activity, treatment response, and radiographic progression of AxSpA, and entails multiple search strings used to identify articles of interest published in PubMed and the Cochrane database up to May 1, 2021. We present the current status of research in serologic biomarkers such as cytokines, adipokines, matrix metalloproteinases, calprotectin, CD74, antibodies, bone turnover markers, and circulating protein fragments of cartilage and connective tissue degradation and other biomarkers. Despite a great deal of work, most serologic results have been disappointing and to date none perform better than CRP. Recent promising preliminary data for some has been published, but require further confirmation. Transcriptomic biomarkers such as micro-RNAs and genetic biomarkers also show promise to assist in diagnosis and possibly for radiographic severity, including a recently developed panel of genetic risk markers used in a polygenic risk score instrument in AS diagnosis. These need further confirmation and application in AS as well as in nr-AxSpA.

Osteoimmunological insights into the pathogenesis of ankylosing spondylitis

Ankylosing spondylitis (AS) is inflammatory arthritis predominantly affecting the spine, which is involved in the disorders of both immune and skeletal systems. The exact pathogenesis of AS is not fully understood. Osteoimmunology is a new subject of study in inflammatory arthritis, in particular the pathogenic events involved in the cross-regulation of both skeletal and immune systems. In this review, we discuss osteoimmunological and pathological changes of AS in the spine that are characterized by altered osteogenesis and osteolytic bone destruction, accompanied by the changes of the immune system. It was revealed that bone cells like mesenchymal stem cells, osteoblast, and osteoclast in crossing talking with immune cells such as T cells, B cells coregulate to the pathogenesis of AS. Further, an array of cytokines and molecules expressed by both skeletal and immune systems contribute to these complex interplays. Understanding the cellular and molecular mechanisms underlying the pathogenesis of AS will lay a foundation for the exploration of the potential new treatment to AS.

Cytokine "fine tuning" of enthesis tissue homeostasis as a pointer to spondyloarthritis pathogenesis with a focus on relevant TNF and IL-17 targeted therapies

A curious feature of axial disease in ankylosing spondylitis (AS) and related non-radiographic axial spondyloarthropathy (nrAxSpA) is that spinal inflammation may ultimately be associated with excessive entheseal tissue repair with new bone formation. Other SpA associated target tissues including the gut and the skin have well established paradigms on how local tissue immune responses and proven disease relevant cytokines including TNF and the IL-23/17 axis contribute to tissue repair. Normal skeletal homeostasis including the highly mechanically stressed entheseal sites is subject to tissue microdamage, micro-inflammation and ultimately repair. Like the skin and gut, healthy enthesis has resident immune cells including ILCs, γδ T cells, conventional CD4+ and CD8+ T cells and myeloid lineage cells capable of cytokine induction involving prostaglandins, growth factors and cytokines including TNF and IL-17 that regulate these responses. We discuss how human genetic studies, animal models and translational human immunology around TNF and IL-17 suggest a largely redundant role for these pathways in physiological tissue repair and homeostasis. However, disease associated immune system overactivity of these cytokines with loss of tissue repair “fine tuning” is eventually associated with exuberant tissue repair responses in AS. Conversely, excessive biomechanical stress at spinal enthesis or peripheral enthesis with mechanically related or degenerative conditions is associated with a normal immune system attempts at cytokine fine tuning, but in this setting, it is commensurate to sustained abnormal biomechanical stressing. Unlike SpA, where restoration of aberrant and excessive cytokine “fine tuning” is efficacious, antagonism of these pathways in biomechanically related disease may be of limited or even no value.

Clinical significance and prognostic value of tumor necrosis factor-α and dickkopf related protein-1 in ankylosing spondylitis

BACKGROUND

Ankylosing spondylitis (AS) frequently occurs in people aged 30-45 years, and its prevalence is generally believed to be between 0.1% and 1.4% globally. At present, the “gold standard” for diagnosis of AS requires the provision of pelvic X-rays, which makes it more difficult to perform in population-based epidemiological studies. Therefore, the identification of serological indicators related to the diagnosis, treatment, and prognosis of AS patients is of great significance.

AIM

To analyze the therapeutic, diagnostic significance and prognostic value of dickkopf-related protein-1 (DKK-1) and tumor necrosis factor-α (TNF-α) in AS.

METHODS

A total of 113 patients with active AS were selected as the research group, and 100 healthy subjects who underwent physical examination were selected as the control group. The levels of DKK-1 and TNF-α in peripheral blood in the two groups were compared. The diagnostic and predictive values of DKK-1 and TNF-α for AS were analyzed with ROC curves, and the factors influencing AS recurrence were analyzed with COX regression.

RESULTS

Before treatment, the research group showed lower DKK-1 levels but higher TNF-α levels than the control group (both ^aP < 0.05). In the research group, DKK-1 was up-regulated and TNF-α was down-regulated after 12 wk of treatment (^aP < 0.05). The area under the curve, sensitivity and specificity of DKK-1 combined with TNF-α for diagnosing AS were 0.934, 82.30% and 97.00%, respectively. Before treatment, the area under the curve, cutoff value, sensitivity and specificity of DKK-1 for predicting the curative effect were 0.825, 68.42 pg/mL, 73.68% and 80.00%, respectively, and those of TNF-α were 0.863, 32.79 ng/L, 92.11% and 77.33%, respectively. DKK-1 and TNF-α levels after treatment were closely related to the curative effect (^aP < 0.05). C-reactive protein, the Bath Ankylosing Spondylitis Disease Activity Index, DKK-1, and TNF-α were risk factors for AS recurrence (^aP < 0.05).

CONCLUSION

DKK-1 and TNF-α are effective in the diagnosis and treatment of AS and are risk factors for its recurrence. In addition, DKK-1 may be a potential target for the diagnosis of AS.

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.